An investigation of different Nd1.8Ce0.2CuO4+δ-Ce0.9Gd0.1O2-δ composite cathodes
Electrochimica Acta 130(2014)439–445
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Electrochimica
Acta
j o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /e l e c t a c t
a
An investigation of different Nd 1.8Ce 0.2CuO 4+?-Ce 0.9Gd 0.1O 2-?composite cathodes
A.P.Khandale,S.S.Bhoga ?
Department of Physics,RTM Nagpur University,Nagpur-440033,India
a r t i c l e
i n f o
Article history:
Received 24January 2014
Received in revised form 4March 2014Accepted 4March 2014
Available online 15March 2014
Keywords:
dc conductivity
electrochemical impedance spectroscopy composite cathode
intermediate-temperature solid oxide fuel cells.
a b s t r a c t
The compositions of (100-x )Nd 1.8Ce 0.2CuO 4+?:(x )Ce 0.9Gd 0.1O 2-?(x =00,10,20,30,40and 50vol.%)com-posite system,synthesized by ball milling appropriate mixture followed by sintering at 1000?C for 4h,are of super?ne crystalline nature (crystallite size 106to 253nm).The dc conductivity decreases with increase in Ce 0.9Gd 0.1O 2-?second phase.The increase in Ce 0.9Gd 0.1O 2-?content in composites reduces the crystal-lite size of Nd 1.8Ce 0.2CuO 4+?.Symmetric cells in the con?guration given by electrode/electrolyte/electrode with gadolinia-doped ceria (GDC)as electrolyte were fabricated by spin coating the ink of cathode.The minimum area speci?c resistance (ASR)value of 0.34 cm 2was obtained at a temperature of 700?C,for (70)Nd 1.8Ce 0.2CuO 4+?:(30)Ce 0.9Gd 0.1O 2-?composite cathode,and directly correlated with optimum dispersion of gadolinia-doped ceria into Nd 1.8Ce 0.2CuO 4+?matrix.
?2014Elsevier Ltd.All rights reserved.
1.Introduction
Intermediate temperature solid oxide fuel cells (IT-SOFCs)are viewed as a promising power generation systems with high ef?ciency and low pollution.Mixed ionic-electronic conductors (MIECs)are considered as the most suitable cathode materials in solid oxide fuel cells (SOFCs)in order to minimize area speci?c resistance (ASR)by enlarging the electrochemical active zones.A change from gas-electrode-electrolyte triple-phase boundary (TPB)to gas-MIEC two-phase boundary (2PB)is directly relevant for IT-SOFCs where cathodic polarization losses become critical [1–3].The 2PB materials may help in decreasing the operating temperature [4].
A 2BO 4(A =rare earth,alkaline earth;
B =transition metal)type MIECs with K 2NiF 4structure are gaining importance in near recent past due to high electronic conductivity,adequate oxygen ion conduction and strong electrocatalytic activity towards oxygen reduction reaction (ORR).Additionally,they exhibit thermal expan-sion coef?cient (TEC)values that are comparable to established oxygen-ion conducting solid electrolytes (Yttria stabilized zirconia (YSZ)and Gadolinium doped ceria (GDC))[5–7].For example,TE
C values for Nd 1.7Sr 0.3CuO 4reported as 13.34×10?6K ?1(20-500?C)and 13.48×10?6K ?1(20-800?C)[8],and for Nd 1.8Sr 0.2NiO 4it is 12.8×10?6K ?1(50-900?C)[9].Cuprates and nickelates
?Corresponding author.Tel.:+917122500083;fax:+917122500736.E-mail address:msrl.physics1@https://www.wendangku.net/doc/cd402638.html, (S.S.Bhoga).
based on K 2NiF 4structure are reported to exhibit good thermo-chemical stability [10].Mixed ionic and electronic conductivity in this class of materials arise from defect equilibrium that can allow signi?cant electronic defects,which is related to oxygen non-stoichiometry.Signi?cant mixed ionic and electronic conductivities with appreciable electrocatalytic activity are reported in Ln 2NiO 4and Ln 2CuO 4systems (where Ln stands for lanthanide elements)[8–14].K 2NiF 4-type compounds containing Co and Fe have been studied extensively [15,16].Soorie et al.studied Nd 2-x Ce x CuO 4+?(0≤x ≤0.2)cathode interfaced with both GDC (Ce 0.9Gd 0.1O 1.95)and LSGM (La 0.9Sr 0.1Ga 0.8Mg 0.2O 3±?)electrolytes [17].The solid solu-bility limit of Ce in Nd 2-x Ce x CuO 4has been reported to be at x =0.2[7,17].
In near recent past,composite cathodes are gaining importance not only due to further reduction in ASR but also to establish good cathode-electrolyte interface.The composite consists of a matrix phase cathode (electronic or MIECs)and a second phase electrolyte.Although effective electrical conductivity decreases with increas-ing Ce 0.8Sm 0.2O 1.9electrolyte in La 1.6Sr 0.4NiO 4+?:Ce 0.8Sm 0.2O 1.9composite cathode the ASR found minimum (0.238 cm 2at 800?C)for 30wt%of Ce 0.8Sm 0.2O 1.9[18].Huang et al.reported best performance of cathode in terms of smallest ASR (0.23 cm 2at 750?C)and impedance for Pr 1.6Sr 0.4NiO 4:20YSZ compos-ite [19].According to Murray et al.,addition of 50vol%GDC in La 0.6Sr 0.4Co 0.2Fe 0.8O 3(LSCF)resulted in ten times increase in ionic conductivity that eventually reduced ASR (0.49 cm 2at 750?C)[20].Patro et al.have optimized the sintering temperature (1000?C)of Pr 0.58Sr 0.42Fe 0.8Co 0.2O 3-?(PSCF)-GDC composite on the basis of
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440 A.P.Khandale,S.S.Bhoga/Electrochimica Acta130(2014)439–445
minimum ASR(0.12 cm2at800?C)[21].They also reported sharp increase in ASR for PSCF<50wt%.Furthermore,the high polariza-tion resistance is assigned to insuf?cient electronic conductivity and low catalytic activity.High ionic conductivity is achieved in conventional and dominant electronic conducting(LaSr)MnO3 (LSM)by GDC impregnation in turn improved ASR[22].The impreg-nation of ion conducting GDC in LSM matrix not only inhibits the growth of LSM grains during sintering but it also increases the TPB leading to signi?cant reduction in ASR[23].
In this work,our objective was to reduce further the ASR of optimized Nd1.8Ce0.2CuO4+?(during earlier work[24])by using the concept of composite cathode.Particularly,the compositions belonging to(100-x)Nd1.8Ce0.2CuO4+?:(x)Ce0.9Gd0.1O2-?(x=10-50)composite system were prepared using microwave com-bustion synthesized Nd1.8Ce0.2CuO4+?and commercially available Ce0.9Gd0.1O2-?nano-powder.Each composition of this system was characterized by XRD,SEM and dc electrical conductivity.The elec-trochemical impedance spectroscopy(EIS)studies were carried on symmetric cell(composite cathode/GDC-electrolyte/composite cathode)to determine temperature and oxygen partial pressure dependent ASR.
2.Experimental
The Nd1.8Ce0.2CuO4+?(NCCO)was prepared by microwave combustion technique as described elsewhere[24].The acetates of cerium,neodymium and copper(purity>99.9%,from Aldrich Chemicals,USA)were used as reagents.Well-dried reagents in requisite stoichiometric ratio(0.5277g(Ce(C2H3O2)3, 4.7125g (Nd((C2H3O2)3and1.6606g Cu((C2H3O2)3)were dissolved in the double distilled deionized water,https://www.wendangku.net/doc/cd402638.html,ter,all the solutions were mixed together and stirred to obtain homogeneous solution using magnetic stirrer.The homogeneous solution was combusted using microwave oven with output power of800W.The com-bustion residue was ground and pressed(2000kg cm?2)to obtain circular discs(pellets)of9mm diameter and1.5mm thickness. The pellets were sintered at1000?C for4h using high tempera-ture furnace(Thermolyne,USA).The10mole%gadolinium doped ceria(GDC)electrolyte nano-powder(Aldrich,USA),as procured, was used as second phase.
The composites(100-x)NCCO:(x)GDC when x=10?40were prepared by taking appropriate vol.%of NCCO and GDC(total vol-ume of composites=0.2cm3).Each mixture was ball milled using zirconia bowl and balls(Pulverisette6,Fritsch,Germany)at200 revolutions per minute(rpm)for2h.The ball-milled?ne powder was pelletized,as described above,and?nally sintered at1000?C for4h to obtain the composite cathode.
All the prepared samples(90NCCO:10GDC,80NCCO:20GDC, 70NCCO:30GDC and60NCCO:40GDC)were characterized by X-ray powder diffraction,PANalytical X’pert PRO,Philips,The Netherlands,using CuK?radiations,scanning electron microscopy, Jeol JSM6380.The effective crystallite sizes(C s)of both the phases in all compositions under study were determined using X’pert Highscore plus software based on the Scherrer formula(Eq.(1)) as described earlier[7]:
C s=0.9
ˇcos?B(1) where ,and?B are X-ray wavelength and Bragg’s angle,respec-tively.Theˇwas determined using relation:
ˇ2=ˇ2m?ˇ2s(2) where,ˇm andˇs are the measured and the standard full width at half maximum(FWHM)of diffracted peak,respectively.The ˇs was estimated from the XRD pattern obtained by running the experiment on a standard silicon sample provided by PANalytical, Netherlands.
A thin platinum?lm on both?at surfaces of the sintered pellet was obtained by dc sputtering,and resulted in good ohmic con-tacts for dc electrical conductivity measurements[7].Prior to the temperature dependent conductivity measurements,the sample was spring-loaded in a ceramic cell holder(Amel,Italy)and heated to700?C for1h for homogenizing the charge carriers.During the cooling cycle,a dwell time of30min was allowed at each set tem-perature to ensure thermal equilibrium in the cells.Ten minutes prior to the end of the dwell time,the resistance was measured using the four-probe method with the help of computer-controlled Keithley6221current source and Keithley2182A nanovoltmeter in delta mode[7].The temperature of the sample during measure-ment was controlled with an accuracy of±1?C using Eurotherm 2216e temperature controller.The tip of a calibrated thermocou-ple was kept in the vicinity of the sample to measure its actual temperature.
The slurry/ink of Nd1.8Ce0.2CuO4+?for electrochemical stud-ies was obtained as follows.1g of Nd1.8Ce0.2CuO4+?powder was mixed with3wt%polyvinyl butyral binder,sodium free corn oil and ethyl methyl ketone.The mixture was then ball-milled using Pulverisette-6(Fritsch,Germany)for2h with300revolutions per minute(rpm).The200zirconia balls of5-mm diameter and80-ml capacity bowl of same material were used.The symmetric cells, with the con?guration given below,were obtained by spin coating the cathode ink on both the?at surfaces of sintered GDC pellet(96% relative density).
NCCO/GDC/NCCO Cell-00
80NCCO:20GDC/GDC/80NCCO:20GDC Cell-20
70NCCO:30GDC/GDC/70NCCO:30GDC Cell-30
60NCCO:40GDC/GDC/60NCCO:40GDC Cell-40 The above mentioned symmetric cells were initially baked at400?C for1h so as to remove the organic binders and sub-sequently sintered at800?C for2h.EIS measurements on the sintered symmetric cells as a parametric function of frequency (0.01?1×106Hz),temperature(500–700?C)and oxygen partial pressure were carried out using a computer-controlled Solartron 1255B FRA in combination with a Solartron SI1287electrochemical interface as described elsewhere[7].
3.Results and Discussion
3.1.X-ray powder diffraction
Typical X-ray powder diffraction(XRD)patterns of 80NCCO:20GDC and70NCCO:30GDC are shown in Figs.1(a) and(b),respectively.A careful look at Figs.1(a)and(b)reveals close matching of characteristic diffracted peaks with the joint committee for powder diffraction standard(JCPDS)data?les No. 01-079-1925and No.01-075-0161corresponding to tetragonal Nd1.8Ce0.2CuO4+?and cubic Ce0.9Gd0.1O1.95,respectively.Further, no peak(s)due to intermediate compound(s)are seen in XRD patterns.A meager peak observed in both the diffractograms (Fig.1(a)and(b)at about38-39?is not due to any one of the reagents.It is interesting to note that the relative intensity of this peak remains same in spite of sintering the composite for longer duration(1000?C for12h).This indicates that the observed peak is not due to any reaction product between Nd1.8Ce0.2CuO4+?and Ce0.9Gd0.1O1.95.A close scrutiny of Figs.1(a)and(b)reveals increase in the relative intensity of diffracted peaks due to GDC with increased its content in composites.The experimental lattice cell constants for NCCO and GDC present in composites are compared in Table1.Evidently,the lattice cell constants a and b correspond-ing to NCCO matched closely with JCPDS data(a=0.39481nm and c=1.20524nm,File No.01-079-1925).Further,the lattice
A.P.Khandale,S.S.Bhoga /Electrochimica Acta 130(2014)439–445
441
Table 1
Comparison of lattice cell constants and crystallite sizes of NCCO (C s(NCCO))and GDC (C s (GDC))for (100-x )NCCO:(x )GDC (x =0–50)composite system.
x (Vol%)
a NCCO (nm)
c NCCO (nm)
a GDC
(nm)
C s (NCCO)(nm)
C s (GDC)(nm)000.394±0.002 1.206±0.003–
253±2107±3100.394±0.004 1.207±0.0020.549±0.007247±3107±2200.392±0.003 1.205±0.0050.548±0.004146±4107±1300.393±0.005 1.203±0.0030.549±0.004112±2106±3400.394±0.002 1.206±0.0040.547±0.007106±2118±250
0.393±0.004
1.207±0.002
0.549±0.005
108±3
135±4
Table 2
Comparison of theoretical ( theor )and experimental ( expt.)densities,d.c.conductiv-ity ( )at 660?C and activation energy of conductivity (E a )for (100-x )NCCO:(x )GDC (x =0–50)composite system.
x (Vol%)
theor.(g/cm 3) expt.(g/cm 3)
(%)
(S cm ?1)
E a (eV)
007.351 6.87±0.0293.450.782±0.0040.093±0.002107.328 6.96±0.0394.970.536±0.0020.104±0.003207.316 6.99±0.0295.540.470±0.0030.143±0.002307.304 6.99±0.0495.700.242±0.0040.204±0.004407.292 6.94±0.0395.170.174±0.0020.241±0.00250
7.280
6.90±0.02
94.78
0.103±0.003
0.255±0.004
cell constant a of GDC is in close agreement with JCPDS data (a =0.5418nm;File No.01-075-0161).The invariance of lattice cell constants of NCCO and GDC,determined from XRD data (Table 1),suggests insolubility of Gd 3+in NCCO and Nd 3+/Cu 2+in GDC.Table 1reveals monotonous decrease in crystallite size of NCCO with increase in GDC content in composites.On the other hand,the crystallite size of GDC remains almost invariant up to x =30,and it increases for x >30.The decrease in crystallite size of NCCO with increased GDC content is due to the presence of latter crystallite in between the crystallites of former during sintering.Similarly,Leng et al.have also reported that the presence of ion conducting GDC in LSM matrix inhibited the growth of LSM grains during sintering [23].Whereas,the growth of submicron-crystallite (GDC)at the cost of adjacent similar (GDC)crystallite takes place during the sintering at high temperature leading to overall increase in the crystallite size of GDC for x >30.The XRD results discussed above suggest that Nd 1.8Ce 0.2CuO 4+?neither reacts with GDC electrolyte nor forms any kind of solid solution,which is in good agreement with the earlier ?nding [7].The maximum sintered density of composite when x =30,as evident from Table 2,is due to the minimum average crystallite size of GDC (Table 1).
3.2.Scanning electron microscopy
The scanning electron microphotographs (SEM)of 80NCCO:20GDC and 70NCCO:30GDC composite cathodes sintered at 800?C for 2h are displayed in Fig.2(a)and (b),respectively.
I n t e n s i t y , a . u .
2Degree
Fig.1.The X-ray powder diffraction patterns of (100-x )NCCO:(x )GDC when (a)x =20and (b)x =30.
The secondary grains (500-800nm)in both the samples are made up of smaller primary crystals and form a network of interconnected grain morphology.Furthermore,the SEM images re?ect almost similar porosity for both the samples,which is in good agreement with density values presented in Table 2.The SEM microphotographs of cathode surface of Cell-00and Cell-30,magni?ed view of cathode of Cell-30and fractured surface across the electrode-electrolyte interface of Cell-30are depicted in Figs.3(a)-(d),respectively.Here,the grains of NCCO and GDC are of submicron-size and indistinguishable (Fig.3(c)).Furthermore,the agglomerated submicron-size grains (Figs.3(c))form lumps of about 1-2?m resulting in nano-pores.The GDC electrolyte is highly dense.Uniform arrangement of porous lumps gave suf?-cient number of sub-micron sized pores (Figs.3(a)and (b)),which resulted in highly porous cathode ?lm.The electrode (thickness ≈27?m)and electrolyte form homogenous contact all along the interface (Fig.3(d).In spite of heating and cooling cycles,four times,we did not observe any cracks or separation between electrode and electrolyte.Almost similar results are observed for Cell-20and Cell-40.
3.3.dc conductivity
In MIECs and composites,both ions and electrons contribute to the total electrical conductivity.However,since electronic con-ductivity is usually much higher than ionic,the total conductivity measured is mainly due to electronic conductivity.The variations of dc conductivity with temperature for all the samples under study,shown in Fig.4,exhibited semiconductor to pseudo-metal phase transition in the temperature range from 600to 650?C.Below this transition temperature they obey the Arrhenius law:
T =( T )0exp
?E a
kT
(3)
where ( T )0,k,T and E a are pre-exponential factor,Boltzmann con-stant,absolute temperature and activation energy,respectively.Since oxygen losses in NCCO are predominant/appreciable above 600?C,the mobile charge carrier density reduces considerably with increase in temperature (>600?C).The decreased effective mobile charge causes decrease in dc conductivity,and so semiconduc-tor to pseudo-metallic transition (Fig.4).Similar semiconductor to pseudo-metal phase transition in NCCO is reported [7].The dc con-ductivity ( )and activation enthalpy (E a )for all compositions of (100-x )NCCO:(x )GDC composite system are compared in Table 2.Evidently,the (E a )decreases (increases)monotonously with increase in GDC content.Increased number of electronically very low conducting GDC electrolyte grains hinders the electronic/hole mobility/transport resulting decrease in overall dc conductivity of composites with x .According to literature addition of GDC electrolyte increases ionic conductivity but it decreases overall con-ductivity of composite cathodes [21].
3.4.Electrochemical impedance spectroscopy
The typical complex impedance plots at various temperatures for Cell-30are shown in Fig.5(a).The exploded view of complex
442
A.P.Khandale,S.S.Bhoga /Electrochimica Acta 130(2014)
439–445
Fig.2.Scanning electron microphotographs of (a)80NCCO:20GDC and (b)70NCCO:30GDC.
Table 3
Comparison of ?tted electrical circuit element values corresponding to EIS data of Cell-00and Cell-30at various temperatures.
Sr.No
T(?C)
R GDC ( cm 2)
R 1( cm 2)
R 2( cm 2)
CPE-T 1(mF cm ?2)
CPE-P 1CPE-T 2(F cm ?2)
CPE-P 2Cell-001700 3.26±0.20.31±0.3 1.01±0.1 2.21±0.020.60±0.0020.84±0.0020.28±0.0032680 3.87±0.30.86±0.1 1.40±0.2 1.88±0.020.56±0.0040.80±0.0070.24±0.0043660 6.70±0.3 1.32±0.2 1.81±0.3 1.84±0.020.58±0.0020.76±0.0030.26±0.00646409.26±0.2 1.79±0.2 2.32±0.1 1.42±0.030.57±0.0050.77±0.0060.18±0.005562014.46±0.2 1.90±0.1 2.94±0.2 1.19±0.030.56±0.0060.76±0.0040.19±0.0036
600
20.61±0.1
2.76±0.2
5.20±3
0.81±0.02
0.55±0.004
0.75±0.005
0.16±0.004
Cell-307700 3.30±0.30.093±0.0050.247±0.003 2.33±0.030.94±0.0030.39±0.0030.69±0.0038680 3.76±0.20.293±0.0030.409±0.007 1.99±0.070.91±0.0050.35±0.0030.67±0.0029660 6.40±0.20.487±0.004 1.013±0.004 1.92±0.030.89±0.0040.33±0.0040.69±0.005106409.65±0.40.679±0.007 1.321±0.007 1.49±0.030.88±0.0070.29±0.0040.67±0.0071162014.02±0.10.809±0.002 2.191±0.003 1.23±0.080.86±0.0030.28±0.0030.66±0.00412
600
19.94±0.3
0.986±0.003
3.961±0.005
1.09±0.07
0.86±0.007
0.26±0.002
0.67±0.002
impedance plot for Cell-30and Cell-00at 680?C,shown in Figs.5(b)and 5(c),can be resolved into two depressed semicircular arcs.This indicates that there are at least two dominating reaction steps during overall oxygen reduction reaction (ORR)at cathode.The
incomplete semicircular arc in the high frequency regime,in gen-eral,(Figs.5(a)-(c))is assigned to charge transport through GDC electrolyte [7,24].A close scrutiny of literature suggested that the mid-frequency semicircle could be attributed to
polarization
Fig.3.Scanning electron microphotographs of cathode surface of (a)Cell-00,(b)Cell-30,magni?ed view of cathode of Cell-30and (c)electrode-electrolyte interface of Cell-30.
A.P.Khandale,S.S.Bhoga /Electrochimica Acta 130(2014)439–445
443
2
2.42.8
3.23.64
1 1.1 1.2
1.3
1.4
1
3
K /10
T
l o g (T / S c m -1 K )
Fig.4.Arrhenius plots for (100-x )NCCO:(x )GDC (x =10–50)composite cathodes.
Fig.5.(a)Electrochemical impedance plots for Cell-30at various temperatures,and experimental data (points)at 680?C,simulated data (lines)and electrical equivalent circuit model for (b)Cell-30and (c)Cell-00.
-0.6
-0.10.40.91.41.91
1.1 1.
2 1.
3 1.
4
-13
K /10
T
l o g (A S R /
c m 2)Fig.6.Arrhenius plots for area speci?c resistance (ASR)of Cell-00,Cell-20,Cell-30an
d Cell-40.
during charge transfer [25,26].The low-frequency semicircle can be attributed to non-charge transfer processes such as oxygen surface exchange and gas phase diffusion through the porous cath-ode layer [27–30].The continuous lines of Fig.5are the complex impedance response simulated using electrical equivalent models shown as inset of Fig.5(b)and (c).R MF /CPE1and R LF /CPE2rep-resent the resistance/capacitance due to mid-and low-frequency arcs,respectively.The R GDC of electrical equivalent circuit repre-sents electrolytic (GDC)resistance.Since simulated magnitudes of R GDC for both the cells (Table 3)are almost same,incomplete high-frequency semicircular arc is attributed to GDC electrolyte similar to earlier ?nding [7,24].From the ?tting results (Table 3),it can also be found that R LF is larger than R MF in the entire tempera-ture range of https://www.wendangku.net/doc/cd402638.html,pared with NCCO electrode,at ?xed temperature,the addition of GDC to NCCO electrode reduces signi?cantly the values of R MF as well as R LF ,but the magnitude of CPE (CPE-T1and CPE-T2)remains almost unchanged (Table 3).The estimated magnitude of capacitance of the order of 10?3F for the mid-frequency arcs and 10?1F for the low-frequency arcs are comparable with respect to the values reported for cathodes [31–36].These results suggest the mid-frequency arc originates from the contribution of charge transfer reaction occurring on the electrode/gas interface (oxygen reduction at the surface of cath-ode).On the other hand,low-frequency arc results due to surface diffusion of the dissociative adsorbed oxygen in accordance with the mechanism suggested for composite cathodes in literature [37,38].The reduction in R MF and R LH indicates (Table 3)that the oxygen reduction reaction process improves with the addition of GDC to NCCO,and the non-charge transfer process (low frequency response)becomes reaction rate-limiting step on the composite cathode.Adler has given a detailed description on impedance anal-yses on MIECs [38].
The normalized ASR of each electrode at each temperature was estimated by taking sum of magnitude of R MF and R LF obtained from Nyquist plots at that temperature (ASR =R MF +R LF ).A comparison of the temperature-dependent ASR (Fig.6)reveals lowest ASR (0.34 cm 2at 700?C)for Cell-30amongst all cells under study (Cell-00,Cell-20and Cell-40)in the entire temperature range of measure-ments.Furthermore,the ASR =0.50 cm 2at 700?C for NCCO is lower than reported ASR ≈5.6 cm 2at 700?C for same composi-tion [17].The reduction in ASR for NCCO of the present study is due to its super?ne crystalline nature.The high ionically conducting GDC phase in the NCCO matrix contributes to increased ionic con-ductivity of composite cathode,which in turn reduces the effective
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A.P.Khandale,S.S.Bhoga /Electrochimica Acta 130(2014)439–445
Table 4
A comparison of ASR value obtained in this study with values reported in the literature for (K 2NiF 4):(oxy-ion conductor)composite cathodes.
Sr.#
Cathode
ASR ( cm 2)
T (?C)
Reference 180Pr 1.6Sr 0.4NiO 4:20(wt%)YSZ
0.23750Huang et al.[19]294Sm 1.8Ce 0.2CuO 4:06(vol%)Ce 0.9Gd 0.1O 1.950.17750Sun et al.[49]370La 1.6Sr 0.4NiO 4+?:30(wt%)Ce 0.8Sm 0.2O 1.90.425750Gong et al.[55]470Ba 1.2Sr 0.8CoO 4+?:30(wt%)Ce 0.9Gd 0.1O 1.9
0.17750Jin and Liu [56]5
70Nd 1.8Ce 0.2Cu 0.5Ni 0.5O 4+?:30(vol%)Ce 0.9Gd 0.1O 2-?
0.34
700
a
a-present study
charge transfer resistance R eff
ct and can be understood by simpli?ed Tanner equation given below [38–40].
R eff ct ≈
BR ct
i (1?V v )
(4)
where B ,R ct , i and V v are grain size of electrolyte (GDC)in composite electrode,intrinsic charge transfer resistance (for pure electronic conducting cathode),ionic conductivity of electrolyte (different than the dense electrolyte)and fractional porosity,respectively.Since the V v is almost same for all the symmetric cells under study (almost similar microstructural features evident from Fig.3(a)and (b)),lowest ASR of Cell-30amongst all is due to rel-atively lower value of R eff ct
resulting from minimum grain size and optimum dispersion of GDC in composite cathode.The optimum dispersion of GDC with minimum crystallite size (Table 1)provides maximum electrochemical reaction sites and so lowest ASR.The observed high performance of the composite electrodes at this composition (70NCCO:30GDC)is consistent with the effective medium percolation theory which predicts the ambipolar trans-port behaviour of composite mixed ionic-electronic conductors as a function of the volume fraction of each of the randomly-distributed constituent phases [34,41].Many studies have investigated the effect of cathode composition on cell performance [34,42–45].The addition of 50wt%GDC to an La 0.6Sr 0.4Co 0.2Fe 0.8O 3-?(LSCF)cathode resulted reduced ASR at low temperatures com-pared with a cathode with 30wt%GDC [42].A mixture of 40vol%LSGM with LSCF offered lower ASR [42].Similarly,ASR optimization is reported in La 0.6Sr 0.4Co 0.2Fe 0.8O 3-?:(36vol%)Ce 0.9Gd 0.1O 2-?[34],La 0.6Sr 0.4Co 0.2Fe 0.8O 3-?:(60wt%)Ce 0.9Gd 0.1O 2-?[46],LaBa 0.5Sr 0.5Co 2O 5+?:(40wt%)Ce 0.9Gd 0.1O 2-?[47],La 1-x Sr x MnO 3:(40wt%)YSZ [48]and Sm 1.8Ce 0.2CuO 4:(06vol%)Ce 0.9Gd 0.1O 1.95[49],Pr 0.58Sr 0.4Fe 0.8Co 0.2O 3??:Ce 0.9Gd 0.1O 1.95(50wt%)[50],(La,Sr)(Co,Fe)O 3:(Ce,Gd)O 3(50vol%)[51].
In order to further clarify the oxygen reduction reaction (ORR)mechanism on the composite cathode,impedance measurements were done as a function of oxygen partial pressure.The linear dependence of log(ASR)with log(P o 2)(at 700?C)shown in Fig.7can be represented by an expression given below:
ASR =ASR 0 P O 2
?n
(5)
According to literature,information on species/steps involved in the ORR at electrode can be drawn from n -values [52].
n =1,
O 2(g)?O 2,abs
(6)n =
12,O 2,abs ?2O abs
(7)n =
38
,O TPB +e ?O ?TPB
(8)n =
14
,O abs +2e +V ??O ?O x
O
(9)n =1
8
,
O ?TPB
+e ?
O 2?
TPB
(10)n =
1
10
,O 2?TPB +V ??O ?O x O
(11)
00.20.40.60.8
1
log (P o 2/ Pa)
1.2log
(P o 2 / Pa )(a)
(b)
Fig.7.Variation of area speci?c resistance (ASR)with oxygen partial pressure for
Cell-00and Cell-30estimated from (a)mid-frequency (MF)and (b)low-frequency (LF)responses.
Oxygen reduction reaction process comprises several steps [38,53].Some of them,which are potential rate limiting steps are mentioned above (Eq.(6-11)).For metal oxide electrodes on solid electrolytes,n =0.25has been attributed to the charge trans-fer process at the TPB,occurring at the current collector/electrode and the electrode/electrolyte interfaces,respectively (Eq.9).n =0.5related to the oxygen adsorption–desorption process,involving oxygen diffusion at the gas cathode surface interface and surface diffusion of intermediate oxygen species related (Eq.7);and n =1to gaseous diffusion of oxygen molecules in the porous structure (Eq.6).As can be seen from Fig.7(b)n ≈0.22and n ≈0.50P o 2dependencies of R MF and R LM are observed.These results strongly support the interpretation of complex impedance results discussed above i.e.the mid-frequency response is due to charge trans-fer step and low-frequency arc be assigned to the non-charge transfer oxygen adsorption-desorption and subsequent diffusion process of overall OOR.Similar rate limiting steps are considered for La 1.6Sr 0.4NiO 4:Ag [54]and Sm 1.8Ce 0.2CuO 4:Ce 0.9Gd 0.1O 1.95[49]composite cathodes.According to literature,observed n =0.1(Eq.(11))for LSM/YSZ composite cathode is attributed to oxygen ion transfer from the triple phase boundary (TPB)to the electrolyte [48].Comparison of the results obtained in Fig.7(a)and (b)reveals that the non-charge process oxygen adsorption–desorption pro-cess is the major rate limiting step for composite cathode under study in the whole range of measurement oxygen partial pres-sure.The 70NCCO:30GDC composite exhibits lowest ASR compared to reports on K 2NiF 4-type based composite cathodes (Table 4)[19,49,55,56].
4.Conclusions
The compositions of (100-x )Nd 1.8Ce 0.2CuO 4+?:(x )Ce 0.9Gd 0.1O 2-?
composite system for varying values of x =00,10,20,30,40and 50(vol.%),synthesized by ball milling,are of super?ne crystallites.Both the Nd 1.8Ce 0.2CuO 4+?and the Ce 0.9Gd 0.1O 2-?are chemically stable against each other at least up to 1000?C.The d.c.(electronic)conductivity decreases with
A.P.Khandale,S.S.Bhoga/Electrochimica Acta130(2014)439–445445
increased x.The lowest ASR value(0.34 cm2)obtained at 700?C for70Nd1.8Ce0.2CuO4+?:30Ce0.9Gd0.1O2-?composite as compared to that for Nd1.8Ce0.2CuO4+?(ASR=0.5 cm2), 80Nd1.8Ce0.2CuO4+?:20Ce0.9Gd0.1O2and60Nd1.8Ce0.2CuO4+?:40Ce 0.9
Gd0.1O2-?is due to optimum dispersion of Ce0.9Gd0.1O2-?in Nd1.8Ce0.2CuO4+?matrix resulting in maximum electrochem-ical reaction zone.The70Nd1.8Ce0.2CuO4+?:30Ce0.9Gd0.1O2-?composite cathode of present study exhibits acceptable performance.
Acknowledgements
The authors are thankful to DST,New Delhi for?nancial support through Indo-UK multi-institutional project No.SR/RC-UK/Fuel-Cell-04/2011/RTM(G)and UGC,New Delhi through SAP.
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螺纹通止规
螺纹通止规 定是:螺纹止规进入螺纹不能超过2.5圈,一般的要实际不得超过2圈,并且用得力度不能大,我们的经验是用拇指和食指轻轻夹持螺纹规以刚好能转动螺纹规的力度为准.力大了就相当于在使用丝锥或牙板了,那样规就用不了几次了. 螺纹通止规 螺纹通止规是适用于标准规定型号的灯头作为灯用附件电光源产品时候的设计和生产、检验的工具设备。 用途 一般用于检验螺纹灯头或灯座的尺寸是否符合标准要求，分别检验螺纹灯头的通规和止规尺寸或灯座的通规或止规尺寸。 工作原理 具体检验要求及介绍详见中国人民国国家标准：GB/T1483.1-2008或 IEC60061-3:2004标准规定容。 操作方法 具体检验要求及介绍详见中国人民国国家标准：GB/T1483.1-2008或 IEC60061-3:2004标准规定容。 通止规
通止规，是量规的一种。作为度量标准，用于大批量的检验产品。 通止规是量具的一种，在实际生产批量的产品若采取用计量量具（如游标卡尺，千分表等有刻度的量具）逐个测量很费事．我们知道合格的产品是有一个度量围的.在这个围的都合格，所以人们便采取通规和止规来测量． 通止规种类 （一）对统一英制螺纹，外螺纹有三种螺纹等级：1A、2A和3A级，螺纹有三种等级：1B、2B和3B级，全部都是间隙配合。等级数字越高，配合越紧。在英制螺纹中，偏差仅规定1A和2A级，3A级的偏差为零，而且1A和2A级的等级偏差是相等的等级数目越大公差越小，如图所示：1B 2B 3B 螺纹基本中径3A 外螺纹2A 1A 1、1A和1B级，非常松的公差等级，其适用于外螺纹的允差配合。 2、2A和2B级，是英制系列机械紧固件规定最通用的螺纹公差等级。 3、3A和3B级，旋合形成最紧的配合，适用于公差紧的紧固件，用于安全性的关键设计。 4、对外螺纹来说，1A和2A级有一个配合公差，3A级没有。1A级公差比2A级公差大50，比3A级大75，对螺纹来说，2B级公差比2A公差大30。1B级比2B级大50，比3B级大75。 （二）公制螺纹，外螺纹有三种螺纹等级：4h、6h和6g，螺纹有三种螺纹等级：5H、6 H、7H。（日标螺纹精度等级分为I、II、III三级，通常状况下为II级）在公制螺纹中，H 和h的基本偏差为零。G的基本偏差为正值，e、f和g的基本偏差为负值。如图所示：公差G H 螺纹偏差基本中径外螺纹f g h e 1、H是螺纹常用的公差带位置，一般不用作表面镀层，或用极薄的磷化层。G位置基本偏差用于特殊场合，如较厚的镀层，一般很少用。 2、g常用来镀6-9um的薄镀层，如产品图纸要6h的螺栓，其镀前螺纹采用6g的公差带。 3、螺纹配合最好组合成H/g、H/h或G/h，对于螺栓、螺母等精制紧固件螺纹，标准推荐采用6H/6g的配合。 （三）螺纹标记M10×1–5g 6g M10×1–6H 顶径公差代号中径和顶径公差代号（相同）中径公差代号。 通止规是两个量具分为通规和止规．举个例子：M6－7h的螺纹通止规一头为通规（T）如果能顺利旋进被测螺纹孔则为合格，反之不合格需返工（也就是孔小了）．然后用止规（Z）如果能顺利旋进被测螺纹孔2.5圈或以上则为不合格反之合格．且此时不合格的螺纹孔应报废，不能进行返工了．其中2.5圈为国家标准，若是出口件最多只能进1.5圈（国际标准）．总之通规过止规不过为合格，通规止规都不过或通规止规都过则为不合格。
感官动词和使役动词
感官动词和使役动词 默认分类2010-05-28 23:14:26 阅读46 评论0 字号：大中小订阅 使役动词，比如let make have就是3个比较重要的 have sb to do 没有这个用法的 只有have sb doing.听凭某人做某事 have sb do 让某人做某事 have sth done 让某事被完成（就是让别人做） 另外： 使役动词 1.使役动词是表示使、令、让、帮、叫等意义的不完全及物动词,主要有make(使,令), let(让), help(帮助), have(叫)等。 2.使役动词后接受词,再接原形不定词作受词补语。 He made me laugh. 他使我发笑。 I let him go. 我让他走开。 I helped him repair the car. 我帮他修理汽车。 Please have him come here. 请叫他到这里来。 3.使役动词还可以接过去分词作受词补语。 I have my hair cut every month. 我每个月理发。 4.使役动词的被动语态的受词补语用不定词,不用原形不定词。 (主)He made me laugh. 他使我笑了。 (被)I was made to laugh by him. 我被他逗笑了。 使役动词有以下用法： a. have somebody do sth让某人去做某事 ??i had him arrange for a car. b. have somebody doing sth.让某人持续做某事。 ??he had us laughing all through lunch. 注意：用于否定名时，表示“允许” i won't have you running around in the house. 我不允许你在家里到处乱跑。 ******** 小议“使役动词”的用法 1. have sb do 让某人干某事 e.g:What would you have me do? have sb/sth doing 让某人或某事处于某种状态，听任 e.g: I won't have women working in our company. The two cheats had the light burning all night long. have sth done 让别人干某事，遭受到 e.g:you 'd better have your teeth pulled out. He had his pocket picked. notes: "done"这个动作不是主语发出来的。 2.make sb do sth 让某人干某事 e.g:They made me repeat the story. What makes the grass grow?
螺纹通止规要求螺纹通规通
螺纹通止规要求螺纹通规通，止规止。 但是如果螺纹通规止，说明什么？ 螺纹止规通，又说明什么？ 我也来说两句查看全部回复 最新回复 ?wpc (2008-11-07 20:11:20) 在牙型正确的前提下螺纹通止规检测螺纹中径 ?lobont (2008-11-08 11:16:32) 对外螺纹而言，螺纹通规是做到中径上偏差，所以能通过就表示产品合格，通不过就表示螺纹做大了，要再修一刀； 螺纹止规做到中径下偏差，所以只能通过2～3牙，如果也通过，就表示外螺纹做小了，产品成为废品 ?qubin8512 (2008-11-18 15:36:05) 螺纹赛规与螺纹环规主要测量螺纹的中径。 ?datafield (2008-11-29 19:12:51) 检具不是万能的，只是方便而已。具体没什么的我有在哪本书上看过，是一本螺纹手册上的。 ?ZYC007 (2009-2-09 20:31:13) 在牙型正确的前提下螺纹通止规检测螺纹中径。 对外螺纹而言，但是如果螺纹通规止，说明螺纹中径大；螺纹止规通，又说明螺纹中径小。 ?WWCCJJ (2009-3-19 09:27:19) 检测的是螺纹的中径,螺纹检测规在检定时,也是检测其中径. ?tanjiren (2009-3-20 22:23:06) 螺纹通止规只能检测螺纹的作用中径,大径和底径等均无法准确测量出来. ?月夜(2009-4-01 21:47:13) 用来测量中径 ?丽萍(2009-4-02 10:11:41)
只能检测工件螺纹的中径 yg196733456 (2009-4-03 09:15:56)原来是测中径的知道了
感官动词的用法
感官动词 1.see, hear, listen to, watch, notice等词，后接宾语，再接省略to的动词不定式或ing形式。前者表全过程，后者表正在进行。句中有频率词时，以上的词也常跟动词原形。 注释:省略to的动词不定式--to do是动词不定式，省略了to,剩下do，其形式和动词原形是一样的，但说法不同。 see sb do sth 看到某人做了某事 see sb doing sth 看到某人在做某事 hear sb do sth 听到某人做了某事 hear sb doing sth 听到某人在做某事 以此类推... I heard someone knocking at the door when I fell asleep. (我入睡时有人正敲门,强调当时正在敲门) I heard someone knock at the door three times. (听到有人敲门的全过程) I often watch my classmates play volleyball after school. (此处有频率词often) （了解）若以上词用于被动语态，须将省略的to还原： see sb do sth----sb be seen to do sth hear sb do sth----sb be seen to do sth 以此类推... We saw him go into the restaurant. → He was seen to go into the restaurant. I hear the boy cry every day. → The boy is heard to cry every day. 2.感官动词look, sound, smell, taste, feel可当系动词，后接形容词。 He looks angry. His explanation sounds reasonable. The cakes smell nice.
NPT螺纹以及检测方法详解
N P T螺纹以及检测方法详 解 Prepared on 22 November 2020
一、目的：规范公司技术员，检验员，操作员对NPT螺纹的了解。 二、适用范围：适用于公司任何NPT螺纹类产品，参考资料为通用管螺 纹和国家标准GB/T12716-2011。 三、目录 1、NPT和NPTF介绍 2、螺纹技术参数参数讲解 3、NPT与NPTF加工工艺 4、NPT和NPTF的检测方法 四、内容： NPT和NPTF螺纹介绍 NPT 是 National (American) Pipe Thread 的缩写，属於美国标准的 60 度锥管 密封螺纹，用於北美地区，美国标准为13)通用管螺纹．国家标准可查阅 GB/T12716-2011。NPTF：美制干密封圆锥管螺。NPTF = National Pipe Thread Fine 称之为一般用途的锥管螺纹，这也是我们以前称之为的布氏锥螺纹。NPTF 螺纹称之为干密封式锥管螺纹，它连接密封的原理是在没有润滑剂或密封填 料情况下完全依靠螺纹自身形成密封，设计意图是使内、外螺纹牙的侧面、 牙顶和牙底同时接触，来达到密封的目的。它们两者的牙型角、斜度等指标 都是相同的，关键是牙顶和牙底的削平高度不一样，所以，量规的设计也是 不一样的。NPTF干密封管螺纹的牙形精度比NPT螺纹高，旋合时不用任何 填料，完全依靠螺纹自身形成密封，螺纹间无任何密封介质。干密封管螺纹 规定有较为严格的公差，属精密型螺纹，仅用在特殊场合。这种螺纹有较高 的强度和良好的密封性，在具有薄截面的脆硬材料上采用此螺纹可以减少断 裂现象。NPTF内、外螺纹牙顶与牙底间没有间隙，是过盈配合，而NPT螺 纹是过渡配合。NPTF螺纹主要用于高温高压对密封要求严格的场所。NPT
英语中感官动词的用法
英语中感官动词的用法 一、感官动词 1、感官动词(及物动词)有：see/notice/look at/watch/observe/listen to/hear/feel(Vt)/taste(Vt)/smell(Vt) 2、连缀动词(含感官不及物动词) be/get/become/feel/look/sound/smell/taste/keep/stay/seem/ appear/grow/turn/prove/remain/go/run 二、具体用法： 1、see, hear, smell, taste, feel,这五个动词均可作连系动词，后面接形容词作表语，说明主语所处的状态。其意思分别为"看/听/闻/尝/摸起来……"。除look之外，其它几个动词的主语往往是物，而不是人。 例如：These flowers smell very sweet.这些花闻起来很香。 The tomatoes feel very soft.这些西红柿摸起来很软。 2、这些动词后面也可接介词like短语，like后面常用名词。 例如：Her idea sounds like fun.她的主意听起来很有趣。 3、这五个感官动词也可作实义动词,除look(当"看起来……"讲时)只能作不及物动词外,其余四个既可作及物动词也可作不及物动词,此时作为实义动词讲时其主语一般为人。 例如:She smelt the meat.她闻了闻那块肉。 I felt in my pocket for cigarettes.我用手在口袋里摸香烟。 4、taste, smell作不及物动词时,可用于"t aste / smell + of +名词"结构,意为"有……味道/气味"。 例如:The air in the room smells of earth.房间里的空气有股泥土味。 5、它们(sound除外)可以直接作名词,与have或take构成短语。 例如：May I have a taste of the mooncakes?我可以尝一口这月饼吗？taste有品位、味道的意思。 例如：I don’t like the taste of the garlic.我不喜欢大蒜的味道。 She dresses in poor taste.她穿着没有品位。 look有外观，特色的意思，例：The place has a European look.此地具有欧洲特色。 feel有感觉，感受的意思，watch有手表，观察的意思。例：My watch is expensive.我的手表很贵。 6、其中look, sound, feel还能构成"look / sound / feel + as if +从句"结构，意为"看起来/听起来/感觉好像……"。 例如：It looks as if our class is going to win.看来我们班好像要获胜了。 7、感官动词+do与+doing的区别： see, watch, observe, notice, look at, hear, listen to, smell, taste, feel + do表示动作的完整性，真实性；+doing 表示动作的连续性，进行性。 I saw him work in the garden yesterday.昨天我看见他在花园里干活了。(强调"我看见了"
通止规的用法及管理
通止规的用法及管理 1、止规 使用前：应经相关检验计量机构检验计量合格后，方可投入生产现场使用。 使用时：应注意被测螺纹公差等级及偏差代号与环规标识公差等级、偏差代号相同（如M24*1.5-6h与M24*1.5-5g两种环规外形相同，其螺纹公差带不相同，错用后将产生批量不合格品)。 检验测量过程：首先要清理干净被测螺纹油污及杂质，然后在环规与被测螺纹对正后，用大母指与食指转动环规，旋入螺纹长度在2个螺距之内为合格，否则判为不合格品。 2、通规 使用前：应经相关检验计量机构检验计量合格后，方可投入生产现场使用。 使用时：应注意被测螺纹公差等级及偏差代号与环规标识的公差等级、偏差代号相同（如M24*1.5-6h与M24*1.5-5g两种环规外形相同，其螺纹公差带不相同，错用后将产生批量不合格品)。 检验测量过程：首先要清理干净被测螺纹塞规油污及杂质，然后在环规与被测螺纹对正后，用大母指与食指转动环规，使其在自由状态下旋合通过螺纹全部长度判定合格，否则以不通判定。 3、注意事项 在用量具应在每个工作日用校对塞规计量一次。经校对塞规计量超差或者达到计量器具周检期限的环规，由计量管理人员收回、标识隔离并作相应的处理措施。 可调节螺纹环规经调整后，测量部位会产生失圆，此现象由计量修复人员经螺纹磨削加工后再次计量鉴定，各尺寸合格后方可投入使用。 报废环规应标识隔离并及时处理，不得流入生产现场。 4、维护与保养 量具（环规）使用完毕后，应及时清理干净测量部位附着物，存放在规定的量具盒内。生产现场在用量具应摆放在工艺定置位置，轻拿轻放，以防止磕碰而损坏测量表面。 严禁将量具作为切削工具强制旋入螺纹，避免造成早期磨损。可调节螺纹环规严禁非计量工作人员随意调整，确保量具的准确性。环规长时间不用，应交计量管理部门妥善保管。
感官动词的用法
1.感官动词用法之一：see, hear, listen to, watch, notice等词，后接宾语，再接动词原形或ing形式。前者表全过程，后者表正在进行。句中有频率词时，以上的词也常跟动词原形。 I heard someone knocking at the door when I fell asleep. (我入睡时有人正敲门) I heard someone knock at the door three times. (听的是全过程) I often watch my classmates play volleyball after school.(此处有频率词often) 若以上词用于被动语态，后面原有动词原形改为带to不定式： We saw him go into the restaurant. →He was seen to go into the restaurant. I hear the boy cry every day. →The boy is heard to cry every day. 2.感官动词用法之二：look, sound, smell, taste, feel可当系动词，后接形容词： He looks angry. It sounds good. The flowers smell beautiful. The sweets taste sweet. The silk feels soft. I felt tired. They all looked tired. 这些动词都不用于被动语态。如：The sweets are tasted sweet.是个病句。注意：如果加介词like,则后不可接形容词，而接名词或代词：
通止规的用法及管理
通止规的用法及管理 令狐采学 1、止规 使用前：应经相关检验计量机构检验计量合格后，方可投入生产现场使用。 使用时：应注意被测螺纹公差等级及偏差代号与环规标识公差等级、偏差代号相同（如M24*1.56h与M24*1.55g两种环规外形相同，其螺纹公差带不相同，错用后将产生批量不合格品)。 检验测量过程：首先要清理干净被测螺纹油污及杂质，然后在环规与被测螺纹对正后，用大母指与食指转动环规，旋入螺纹长度在2个螺距之内为合格，否则判为不合格品。 2、通规 使用前：应经相关检验计量机构检验计量合格后，方可投入生
产现场使用。 使用时：应注意被测螺纹公差等级及偏差代号与环规标识的公差等级、偏差代号相同（如M24*1.56h与M24*1.55g两种环规外形相同，其螺纹公差带不相同，错用后将产生批量不合格品)。 检验测量过程：首先要清理干净被测螺纹塞规油污及杂质，然后在环规与被测螺纹对正后，用大母指与食指转动环规，使其在自由状态下旋合通过螺纹全部长度判定合格，否则以不通判定。 3、注意事项 在用量具应在每个工作日用校对塞规计量一次。经校对塞规计量超差或者达到计量器具周检期限的环规，由计量管理人员收回、标识隔离并作相应的处理措施。 可调节螺纹环规经调整后，测量部位会产生失圆，此现象由计量修复人员经螺纹磨削加工后再次计量鉴定，各尺寸合格后方
可投入使用。 报废环规应标识隔离并及时处理，不得流入生产现场。 4、维护与保养 量具（环规）使用完毕后，应及时清理干净测量部位附着物，存放在规定的量具盒内。生产现场在用量具应摆放在工艺定置位置，轻拿轻放，以防止磕碰而损坏测量表面。 严禁将量具作为切削工具强制旋入螺纹，避免造成早期磨损。可调节螺纹环规严禁非计量工作人员随意调整，确保量具的准确性。环规长时间不用，应交计量管理部门妥善保管。
感官动词
感官动词的概念和相关考点 1、什么是感官动词？ 听觉：listen to、hear 视觉：look at、seem、watch 嗅觉：smell 触觉：feel、touch 味觉：taste 2、感官动词如何正确使用？ Tom drove his car away. →I saw him drive away. (全过程) 用法一：somebody did sth + I saw this I saw somebody do something. Tom was waiting for the bus. →I saw Tom waiting for the bus. (看不到全过程) 用法二：somebody was doing sth + I saw this I saw somebody doing something 练习： 一、句子翻译 1. I didn,t hear you come in. 2. I suddenly felt sth touch me on the shoulder. 3. I could hear it raining. 4. Listen to the birds singing. 5. Can you smell sth burning? 6. I found Sue in my room reading my letters. 二、灵活运用 1. I saw Ann waiting for the bus. 2. I saw Dave and Helen playing tenins. 3. I saw Clair having her meal. 三、选择最佳选项 1. Did anybody see the accident (happen/happening)? 2. We listen to the old man (tell/telling) his story from beginning to the end. 3. Listen! Can you hear a baby (cry/crying)? 4.—Why did you turn around suddenly? — I heard someone (call/calling) my name. 5. We watched the two men (open/opening) a window and (climb/climbing) through it into house. 6. When we got there, we found our cat (sleep/sleeping) on the table. 四、感官动词的被动语态 Oh，the milk is tasted strange.
感官动词用法
我们学过了五个与人的感觉有关的动词，它们是look，sound，smel l，taste，feel，我们可称之为“感官”动词。它们的用法有着许多相同点，但也有不同之处，现就此作一小结。 一、这五个动词均可作连系动词，后面接形容词作表语，说明主语所处的状态。其意思分别为“看/听/闻/尝/摸起来……”。除loo k之外，其它几个动词的主语往往是物，而不是人。例如：These flowers smell very sweet. 这些花闻起来很香。 The tomatoes feel very soft. 这些西红柿摸起来很软。 The music sounds beautiful. 二、这些动词后面也可接介词like短语，like后面常用名词。例如： Her idea sounds like fun. 她的主意听起来很有趣。 He looks like his father. 三、这五个感官动词也可作实义动词，除look（当“看起来……”讲时）只能作不及物动词外，其余四个既可作及物动词也可作不及物动词，其主语通常是人。例如： She smelt the meat. 她闻了闻那块肉。
I felt in my pocket for cigarettes. 我用手在口袋里摸香烟。 He tasted the soup and added some salt. Miss Wang asked us to look at the blackboard. 四、taste，smell作不及物动词时，可用于“taste / smell + of + 名词”结构，意为“有……味道 / 气味”。例如： The air in the room smells of earth. 房间里的空气有股泥土味。 The bread taste of sugar. 五、它们（sound除外）可以直接作名词，与have或take构成短语。例如： May I have a taste of the mooncakes？我可以尝一口这月饼吗？ May I have a look at your photo? 六、其中look，sound，feel还能构成“look / sound / feel + as if +从句”结构，意为“看起来/听起来/ 感觉好像……”。例如：
通止规的用法及管理修订稿
通止规的用法及管理 WEIHUA system office room 【WEIHUA 16H-WEIHUA WEIHUA8Q8-
通止规的用法及管理 1、止规 使用前：应经相关检验计量机构检验计量合格后，方可投入生产现场使用。 使用时：应注意被测螺纹公差等级及偏差代号与环规标识公差等级、偏差代号相同（如M24*与M24*两种环规外形相同，其螺纹公差带不相同，错用后将产生批量不合格品)。 检验测量过程：首先要清理干净被测螺纹油污及杂质，然后在环规与被测螺纹对正后，用大母指与食指转动环规，旋入螺纹长度在2个螺距之内为合格，否则判为不合格品。 2、通规 使用前：应经相关检验计量机构检验计量合格后，方可投入生产现场使用。 使用时：应注意被测螺纹公差等级及偏差代号与环规标识的公差等级、偏差代号相同（如M24*与M24*两种环规外形相同，其螺纹公差带不相同，错用后将产生批量不合格品)。 检验测量过程：首先要清理干净被测螺纹塞规油污及杂质，然后在环规与被测螺纹对正后，用大母指与食指转动环规，使其在自由状态下旋合通过螺纹全部长度判定合格，否则以不通判定。 3、注意事项
在用量具应在每个工作日用校对塞规计量一次。经校对塞规计量超差或者达到计量器具周检期限的环规，由计量管理人员收回、标识隔离并作相应的处理措施。 可调节螺纹环规经调整后，测量部位会产生失圆，此现象由计量修复人员经螺纹磨削加工后再次计量鉴定，各尺寸合格后方可投入使用。 报废环规应标识隔离并及时处理，不得流入生产现场。 4、维护与保养 量具（环规）使用完毕后，应及时清理干净测量部位附着物，存放在规定的量具盒内。生产现场在用量具应摆放在工艺定置位置，轻拿轻放，以防止磕碰而损坏测量表面。 严禁将量具作为切削工具强制旋入螺纹，避免造成早期磨损。可调节螺纹环规严禁非计量工作人员随意调整，确保量具的准确性。环规长时间不用，应交计量管理部门妥善保管。
英语感官动词用法大全!
在基础英语写作中往往有学生对谓语的选用有一定困惑，其中就有一类特殊的动词：感官动词。今天就由来为大家把其用法进行一下总结： (A)感官动词(及物动词)有： see/notice/look at/watch/observe/listen to/hear/feel(Vt)/taste(Vt)/smell(Vt) (B)连缀动词(含感官不及物动词) be/get/become/feel/look/sound/smell/taste/keep/stay/seem/ appear/grow/turn/prove/remain/go/run 一、see, hear, feel, watch, look,这五个动词均可作 连系动词，后面接形容词作表语，说明主语所处的状态。其意思分别为"看/听/闻/尝/摸起来……" look之外，其它几个动词的主语往往是物，而不是人。 例如： These flowers smell very sweet.这些花闻起来很香。 The tomatoes feel very soft.这些西红柿摸起来很软。 二、这些动词后面也可接介词like短语，like后面常用名词。 例如： Her idea sounds like fun.她的主意听起来很有趣。 三、这五个感官动词也可作实义动词,除look(当"看起来……"讲时)只能作不及物动词外,其余四个既可作及物动词也可作不及物动词,此时作为实义动词讲时其主语一般为人。(和1有区别) 例如: She smelt the meat.她闻了闻那块肉。 I felt in my pocket for cigarettes.我用手在口袋里摸香烟。 四、taste, smell作不及物动词时,可用于"taste / smell + of +名词"结构,意为"有……味道/气味"。 例如: The air in the room smells of earth.房间里的空气有股泥土味。 五、它们(sound除外)可以直接作名词,与have或take构成短语。 例如: May I have a taste of the mooncakes?我可以尝一口这月饼吗? taste有品位，味道的意思 例：I don't like the taste of the garlic. 我不喜欢大蒜的味道。 She dresses in poor taste.她穿着没有品位。 look有外观，特色的意思 例：The place has a European look.此地具有欧洲特色。 feel有感觉，感受的意思 watch有手表，观察的意思 例：My watch is expensive.我的手表很贵。 六、其中look, sound, feel还能构成"look / sound / feel + as if +从句"结构，意为"看起来/听起来/感觉好像……"。 例如：
螺纹规使用方法
螺纹规使用方法 一、目的 规范塞规、环规使用的操作方法，保证测量结果的准确性。螺纹塞规使用者应根据操作规范要求，确保操作过程正确，并负责仪器的维护和保养。 二、说明 螺纹规又称螺纹通止规、螺纹量规，通常用来检验判定螺纹的尺寸是否合格。 螺纹规根据所检验内外螺纹分为螺纹塞规和螺纹环规，目前我们所使用的只有螺纹塞规。 图1 三、使用方法 1、选择螺纹规时，应选择与被测螺纹相匹配的规格。 2、使用前，先清理干净螺纹规和被测螺纹表面的油污、杂质等。 3、使用时，使螺纹规的通端（止端）与被测螺纹对正后，用大拇指与食指转动螺纹规或被 测零件，使其在自由状态下旋转。通常情况下（无被测零件的螺纹的图示说明时），螺纹 规（通端）的通规可以在被测螺纹的任意位置转动,通过全部螺纹长度则判定为合格，否 则为不合格品;在螺纹规（止端）的止规与被测螺纹对正后，旋入螺纹长度在2个螺距之 内止住为合格，不可强行用力通过，否则判为不合格品。（有被测零件的图示说明时，应 按照图示说明做判定。） 图2 图3 图中英文字母“GO”或“T”:表 示螺纹塞规的通端。 图中“G 3/8-19”或“M3 6H” 表示该螺纹规规格. 图中英文字母“NO GO”或“Z”: 表示螺纹塞规的止端。 螺纹塞规
4、检验工件时旋转螺纹规不能用力拧，用三只手指自然顺畅地旋转，止住即可，螺纹规退 出工件最后一圈时也要自然退出，不能用力拔出螺纹规,否则会影响产品检验结果的误差,螺纹规的损坏。 图4 图5 如上图4操作方法是正确的，图5是错误的，无需手握。 5、使用完毕后，及时清理干净螺纹规的通端（止端）的表面附着物，并存放在工具柜的量 具盒内。 四、注意事项 1、被测件螺纹公差等级及偏差代号必须与塞规标识公差等级、偏差代号相同，才可使用。 2、只有当通规和止规联合使用，并分别检验合格，才表示被测螺纹合格。 3、应避免与坚硬物品相互碰撞，轻拿轻放，以防止磕碰而损坏测量表面。 4、严禁将螺纹规作为切削工具强制旋入螺纹，避免造成早期磨损。 5、螺纹规使用完毕后，应及时清理干净测量部位附着物，存放在规定的量具盒内。 五、维护和保养 1、每月定期涂抹防锈油，以保证表面无锈蚀、无杂质（我们的螺纹规使用频繁且所 处环境干净无需上油保护）。 2、所有的螺纹规必须经计量校验机构校验合格后并在校验有效期内，方可使用。 3、损坏或报废的螺纹规应及时反馈处理，不得继续使用。 4、经校对的螺纹规计量超差或者达到计量器具周检期的螺纹规，由计量管理人员收回 并做相应的处理。
英语中的感官动词的用法
感官动词表示人的感官动作，可作完全及物动词或不完全及物动词，例如：see/look/watch/notice/observe, hear/listen to, taste, smell, feel/touch. 一、感官动词经常和情态动词can 连用，例如： hear: Can you hear that? 你能听到吗？ see: I can't see much. 我看不太清楚。 feel: I can feel the baby moving inside me. 我能感觉到婴儿在我体内移动。 二、感官动词用于进行时，表明主语或感知者集中在一个特别的对象上，是一种自愿的动作，常见的有listen to, look at, touch, smell 和taste，例如： listen to: He is listening to the radio. 他正在听收音机。 look at: They are looking at the picture. 他们正在看这幅画。 touch: She is touching her cat. 她正在抚摸她的猫。 smell: She is smelling the flowers. 她在闻花。 taste:
We are tasting champagne. 我们正在品尝香槟。 并不是所有的感官动词都可以用进行时，例如： 误：She was hearing a noise. 误：He was seeing a woman in the rain. 但当hear 在表达一种经历时，可以用进行时；see 在表达与人见面或是约会，可以用进行时，等等，例如： hearing: She was always hearing voices in her head. 她脑子里总有声音。 seeing: She is seeing the doctor. 她正在看医生。 He was seeing another woman. 他在和另一个女人约会。 三、感官动词的特殊用法 1、感官动词+ 宾语+ 不带to 不定式，例如： We heard you leave. 我们听见你走了。 解析：此句强调的重点是“We heard". I saw her go. 我看见她走了。 解析：此句强调的重点是"I saw" . 2、感官动词 + 宾语 + 动名词，例如： We heard you leaving. 我们听见你走了。 解析：此句强调的重点是“you leaving",相当于 We heard you when you
感官动词用法
“感官”动词用法小结 我们学过了五个与人的感觉有关的动词,它们就是look,sound,smell,ta ste,feel,我们可称之为“感官”动词。它们的用法有着许多相同点,但也有不同之处,现就此作一小结。 一、这五个动词均可作连系动词,后面接形容词作表语,说明主语所处的状态。其意思分别为“瞧/听/闻/尝/摸起来……”。除look之外,其它几个动词的主语往往就是物,而不就是人。例如: These flowers smell very sweet、这些花闻起来很香。 The tomatoes feel very soft、这些西红柿摸起来很软。 The music sounds beautiful、 二、这些动词后面也可接介词like短语,like后面常用名词。例如: Her idea sounds like fun、她的主意听起来很有趣。 He looks like his father、 三、这五个感官动词也可作实义动词,除look(当“瞧起来……”讲时)只能作不及物动词外,其余四个既可作及物动词也可作不及物动词,其主语通常就是人。例如: She smelt the meat、她闻了闻那块肉。
I felt in my pocket for cigarettes、我用手在口袋里摸香烟。 He tasted the soup and added some salt、 Miss Wang asked us to look at the blackboard、 四、taste,smell作不及物动词时,可用于“taste / smell + of + 名词”结构,意为“有……味道/ 气味”。例如: The air in the room smells of earth、房间里的空气有股泥土味。The bread taste of sugar、 五、它们(sound除外)可以直接作名词,与have或take构成短语。例如: May I have a taste of the mooncakes？我可以尝一口这月饼不？May I have a look at your photo? 六、其中look,sound,feel还能构成“look / sound / feel + as if +从句”结构,意为“瞧起来/听起来/ 感觉好像……”。例如: It looks as if our class is going to win、瞧来好像我们班要获胜了It sounds as if the rain is very heavy、
HGS型钢筋直螺纹滚丝机使用说明书
H G S型钢筋直螺纹滚丝 机使用说明书 集团标准化办公室：[VV986T-J682P28-JP266L8-68PNN]
HGS-40型钢筋直螺纹滚丝机使用说明书 一．用途 HGS-40型钢筋直螺纹滚丝机。主要用于建筑工程带肋钢滚轧直螺纹丝头，是实现钢筋连接的关键设备。可加工直径16-40mm的HRB335和HRB400级带肋钢筋。 二．特点 HGS-40型钢筋直螺纹滚丝机，可一次装夹完成从剥肋到滚轧螺纹的加工过程。加工螺纹的牙形饱满，尺寸精度高，机械强度高。 既可加工正扣螺纹，也可加工反扣螺纹。 本机操作简单、结构紧凑、工作可靠，具有独特的刀具自动开合机构。 可加工直径范围为16－40mm的HRB335和HRB400级钢筋。 三．结构 HGS－40型钢筋直螺纹滚丝机，由机架、夹紧钳、导轨、滑板、摆线针轮减速机、剥肋滚轧头、进给机构、自动开合机构、行程限位机构、冷却系统、电器控制箱、控制系统等部分组成。
四．主要技术参数 1．加工钢筋直径范围：φ16-φ40mm 2．主电机功率： KW 3．配用电源：三相380V 50Hz 4．主轴转速：40-62r／min 5．最大加工长度：80mm 6．重量：560kg 五．使用方法 （一）加工前的准备 1．按要求接好电源线和接地线，接通电源。电源为三相380V 50Hz的交流电源，为保证人身安全请使用带漏电保护功能的自动开关。 2．冷却液箱中，加足溶性冷却液(严禁加油性冷却液）。
（二）空车试转 1．接通电源。检查冷却水泵工作是否正常。 2．操作按钮，检查电器控制系统工作是否正常。 （三）加工前的调整 1．根据所加工钢筋的直径，调换与加工直径相适应的滚丝轮。滚丝轮与加工钢筋直径的关系见表一： 2．调换滚丝轮的同时，调换与滚丝轮螺距相适宜的垫圈，以保证螺距的正确性，螺距与垫圈厚度的关系见表二： 3．滚丝轮与加工直径相适应后，将与钢筋相适应的对刀棒插入滚轧头中心，调整滚丝轮使之与对刀棒相接触，抽出对刀棒，拧紧螺钉，压紧齿圈，使之不得移动。 4．对于固定定位盘的设备根据所加工钢筋直径，调换与加工直径相适应的定位盘（定位盘上打印有加工直径）。对于可调整定位盘的设备按定位盘刻度调整到相应的刻度，当剥肋刀磨损时还需要进行微调。 5．根据所加工钢筋规格，调整剥肋行程档块的位置，保证剥肋长度达到要求值。剥肋长度与钢筋规格的关系见表三：
螺纹环规(通规止规)的使用方法
一、螺纹环规是一种“量具”，是用来检测标准外螺纹中径的，两个为一套，一个通规，一个止 规。两个环规的内螺纹中径分别按照标准螺纹中径的最大极限尺寸和最小极限尺寸制造的，精度非常高。 二、使用方法 1、通规使用前： 应经相关检验计量机构检验计量合格后，方可投入生产现场使用。 使用时：应注意被测螺纹公差 等级及偏差代号与环规标识的公差等级、偏差代号相同（如M24 ×1.5 6h 与M24×1.5 5g 两种环 规外形相同,其螺纹公差带不相同,错用后将产生批量不合格品)。 检验测量过程： 首先要清理干净被测件螺纹油污及杂质，然后在环规与被测件螺纹对正后， 用大拇指与食指转动环规，使其在自由状态下旋合通过螺纹全部长度判定合格，否则以不通判定。 2、止规使用前： 应经相关检验计量机构检验计量合格后，方可投入生产现场使用。 使用时： 应注意被测件螺纹公差等级及偏差代号与环规标识公差等级、偏差代号相同。 检验测量过程： 首先要清理干净被测螺纹油污及杂质，然后在环规与被测螺纹对正后，用大拇指与食指转动环规，旋入螺纹长度在2个螺距之内后止住为合格，否则判为不合格品。 3、通规可以在螺纹的任意位置转动自如，止规拧一至两三圈，（可能有时还能多拧一两圈，但螺纹头部没出环规端面）就拧不动了，这时说明你检测的外螺纹中径正好在“公差带”内，是合格的产品。 4、只有当通规和止规联合使用，并分别检验合格，才表示被测工件合格。 三、维护和保养 螺纹环规使用完毕后，应及时清理干净测量部位附着物，存放在规定的量具盒内。环规使用时应轻拿轻放，环规严禁套在坚硬物品上面旋转。严禁将环规强制旋入螺纹，避免造成早期磨损，确保环规的准确性。长时间不使用，应涂上防锈油。 图中英文字母“T”:表示螺纹环规的通规。 图中英文字母“Z”:表示螺纹环规的止规。 图中“MJ10×1.5 6g”及“7/8-6ACME”表示该螺纹环规的规格。 使用螺纹环规口诀： 通规通；止规止！
英语中感官动词的用法
英语中感官动词的用法 二、具体用法： 1、see, hear, smell, taste, feel,这五个动词均可作连系动词，后面接形容词作表语，说明主语所处的状态。其意思分别为"看/听/闻/尝/摸起来……"。除look之外，其它几个动词的主语往往是物，而不是人。 例如：These flowers smell very sweet.这些花闻起来很香。 The tomatoes feel very soft.这些西红柿摸起来很软。 2、这些动词后面也可接介词like短语，like后面常用名词。 例如：Her idea sounds like fun.她的主意听起来很有趣。 3、这五个感官动词也可作实义动词,除look(当"看起来……"讲时)只能作不及物动词外,其余四个既可作及物动词也可作不及物动词,此时作为实义动词讲时其主语一般为人。 例如:She smelt the meat.她闻了闻那块肉。 I felt in my pocket for cigarettes.我用手在口袋里摸香烟。 4、taste, smell作不及物动词时,可用于"t aste / smell + of +名词"结构,意为"有……味道/气味"。 例如:The air in the room smells of earth.房间里的空气有股泥土味。 5、它们(sound除外)可以直接作名词,与have或take构成短语。 例如：May I have a taste of the mooncakes?我可以尝一口这月饼吗？taste有品位、味道的意思。 例如：I don’t like the taste of the garlic.我不喜欢大蒜的味道。 She dresses in poor taste.她穿着没有品位。 look有外观，特色的意思，例：The place has a European look.此地具有欧洲特色。 feel有感觉，感受的意思，watch有手表，观察的意思。例：My watch is expensive.我的手表很贵。 6、其中look, sound, feel还能构成"look / sound / feel + as if +从句"结构，意为"看起来/听起来/感觉好像……"。 例如：It looks as if our class is going to win.看来我们班好像要获胜了。 7、感官动词+do与+doing的区别： see, watch, observe, notice, look at, hear, listen to, smell, taste, feel + do表示动作的完整性，真实性；+doing 表示动作的连续性，进行性。 I saw him work in the garden yesterday.昨天我看见他在花园里干活了。(强调"我看见了"这个事实) I saw him working in the garden yesterday.昨天我见他正在花园里干活。（强调"我见他正干活"这个动作）