销盘式高温高速摩擦磨损试验机的设计7-科技文原文.pdf
销盘式高温高速摩擦磨损试验机的设计【带CAD图纸设计说明书】
收藏
资源目录
压缩包内文档预览：
编号：40908471
类型：共享资源
大小：5.49MB
格式：ZIP
上传时间：2020-01-14
上传人：QQ24****1780
认证信息
个人认证
王**（实名认证）
浙江
IP属地：浙江
50
积分
- 关 键 词：
-
带CAD图纸设计说明书
销盘式
高温
高速
摩擦
磨损
试验
设计
CAD
图纸
说明书
- 资源描述：
-
销盘式高温高速摩擦磨损试验机的设计【带CAD图纸设计说明书】,带CAD图纸设计说明书,销盘式,高温,高速,摩擦,磨损,试验,设计,CAD,图纸,说明书
- 内容简介：
-
Surface and Coatings Technology 167 (2003) 59670257-8972/03/$ - see front matter ? 2002 Elsevier Science B.V. All rights reserved.doi:10.1016/S0257-8972(02)00882-4Corrosion resistance of ZrN films on AISI 304 stainless steel substrateWen-Jun Chou, Ge-Ping Yu, Jia-Hong Huang*Department of Engineering and System Science, National Tsing Hua University, Hsinchu 300, Taiwan, ROCReceived 28 June 2002; accepted in revised form 6 December 2002AbstractThe corrosion resistance of ion-plated Zr, ZrN and ZrNyZr films on commercial AISI 304 stainless steel has been investigatedby electrochemical measurement. The electrolyte, 0.5 M H SOcontaining 0.05 M KSCN, was used for the potentiodynamic24polarization. The potentiodynamic scan was conducted from y800 to 800 mV (SCE) with scan rate ranging from 10 to 600mVymin. The NyZr ratios of the ZrN films determined by X-ray photoelectron spectroscopy (XPS) were essentially stoichiometric.The composition depth profiles measured by secondary ion mass spectrometry (SIMS) indicated that the compositions in the ZrNfilms were uniform from the film surface to the 304 stainless steel substrate. Experimental results showed that the corrosioncurrent density Iand passive current density I increased with increasing polarization scan rate for the bare AISI 304 stainlesscorrpsteel specimens. Compared with the bare substrate, the Iand Ifor the coated specimens decreased at least 1 order ofcorrpmagnitude. The bi-layer ZrNyZr coating possessed the highest corrosion resistance among the three coated-specimens. Becauseof the cathodic control of the galvanic corrosion, the corrosion potential of the coating specimens was slightly higher than that ofbare metal substrate. The corrosion power Q, i.e. the integrated electric charge per unit area of the specimen during potentiodynamicpolarization test, was an effective index to evaluate the corrosion resistance of the coated stainless steel substrate. The pinholedensity played a significant role in corrosion resistance of the transition metal nitride coatings. Normalized critical passive currentdensity (NI) was closely related to the exposure area, and a linear relationship between Q and NIwas held.critcrit? 2002 Elsevier Science B.V. All rights reserved.Keywords:ZrN; Corrosion; Potentiodynamic polarization; Scan rate; Pinhole1. IntroductionThe transition metal nitride coatings have some excel-lent properties, such as high hardness, good wear resis-tance,chemicalstability,corrosionresistanceandattractive colors, and therefore are widely used in indus-try in the current decade, especially TiN coating. Morerecently, ZrN started to attract more attention for itsbetter corrosion resistance, comparable mechanical prop-erties and warmly golden color, compared to the corre-sponding properties of TiN film w14x.Vapor deposition methods including PVD and CVDare the popular techniques used to prepare transitionmetal nitride films. It is well known that PVD or CVDcoatings normally have numerous inherent microscopic*Corresponding author. Present address: 101 Kuang Fu Road, Sec.2,Hsinchu,Taiwan;Tel.:q886-35715131x4274;fax:q886-35720724.E-mail address: .tw (J.-H. Huang).defects, e.g. pinholes or porosity w5x, which are detri-mental to a corrosion protective film. Localized corro-sion would initiate at these sites, when the corrosivemedium penetrates through the pinhole and reaches themetal substrate underneath.Several ways for reducing the pinhole rate, pinholearea per unit coating area, have been proposed such as:increasing the coating thickness w68x; modifying thefilm structure from columnar to equiaxed w9x; controllingthe bias potential during the film deposition w1012x;and multilayering w10,11,13,14x.Many techniques have been proposed to evaluate thecorrosion resistance and pinhole rate of the coatingsw6,7,11,1417x. The method of potentiodynamic polari-zation with varying scan rate was introduced in thepresent study. By changing the potentiodynamic polari-zation rate, one may obtain useful thermodynamic andkinetic information simultaneously. The pinhole rate can60W.-J. Chou et al. / Surface and Coatings Technology 167 (2003) 5967Table 1Summary of electrochemical testing conditions and testing resultsMaterialScan rateEcorrIcorrIp(mVymin)wmV(SCE)x(mAycm )2(mAycm )2304SS10y44735.83.320y44539.017.450y44460.9101.9100y44969.063.6600y45495.21172.7Zry304SS10y43610.62.520y44123.83.550y45112.94.9100y43316.312.0600y43411.026.7ZrNy304SS10y4331.24.720y4384.13.750y4381.85.3100y4353.76.7600y4426.541.9ZrNyZry304SS10y4371.80.620y4310.54.650y4321.216.7100y4351.54.4600y4371.317.6Electrolyte: 0.5 M H SO containing 0.05 M KSCN was used for24the potentiodynamic polarization conducting from y800 to 800 mV.Fig. 1. The AFM topographic image of ZrN-coated specimen. The surface roughness of the specimen is 4.97 nm.be evaluated by critical passive current density w6,7xdefined as:Ifilmy304SS.critNIscritI304SS.critwhere NIis the normalized critical passive currentcritdensity, I(filmy304SS) is the critical passive currentcritdensity for the film-coated specimen; I(304SS) is thecritcritical passive current density for the bare 304 stainlesssteel substrate.The aim of the present study is to investigate thecorrosion resistance of ion-plated Zr, ZrN and ZrNyZrfilms on commercial AISI 304 stainless steel substrates.The pinhole rate is also examined with various poten-tiodynamic polarization tests on the coatings.2. Experimental details2.1. MaterialsA commercial AISI 304 mirror-like polished stainlesssteel was used as substrate material. The material had acomposition of 0.1% Cu, 0.14% Co, 0.44% Si, 1.18%Mn, 8.37% Ni, 18.57% Cr and the balance being Fe.Prior to the coating process, the specimens were ultra-sonically cleaned in acetone and ethanol progressively,each for 5 min, and dried for approximately 20 min ina pre-vacuum dryer.The coating process was carried out in a hollowcathode discharge ion plating (HCD-IP) system, madeby VMC-TIGOLD Co., Japan. The coating system andprocess have been described elsewhere w11,18x. Theselection of the deposition conditions was based on theearlier research w18x where the microstructure and prop-erties of ZrN on Si (100) substrate were investigatedthoroughly with respect to substrate bias ranging fromfloating to y300 V. The substrate bias at y50 Vshowed the optimum properties. In this study, the spec-imens were deposited at 350 8C, the HCD gun powerwas 6 kW, substrate bias was y50 V, and Ar and N261W.-J. Chou et al. / Surface and Coatings Technology 167 (2003) 5967Fig. 2. The potentiodynamic polarization curves for: (a) bare 304 stainless steel; (b) Zry304SS; (c) ZrNy304SS; and (d) ZrNyZry304SS withvarious scan rate in solution 0.5 M H SO containing 0.05 M KSCN.24partial pressures were 0.133 and 0.0266 Pa, respectively.The durations for depositing Zr and ZrN were 36 and40 min, respectively, which were chosen to control thefilm thickness for each layer to be 600 nm. For the bi-layer ZrNyZr specimens, the durations for depositing Zrand ZrN were reduced and the total coating thicknesswas controlled to be the same as single-layer specimens.The composition depth profiles of ZrN films wereobtainedusingsecondaryionmassspectrometry(SIMS), and the thickness of both Zr and ZrN wasdetermined from the SIMS profiles. The NyZr ratioswere measured by X-ray photoelectron spectrometry(XPS). The surface morphology of coated specimenswas observed by atomic force microscopy (AFM).2.2. Electrochemical testsPrior to the electrochemical test, the specimens wereultrasonically cleaned in acetone. The potentiodynamicpolarization tests were preformed on all specimens,including bare AISI 304 stainless steel, using an EG&G263A electrochemical apparatus. The test cell setupfollowed the ASTM Standard G5 w19x. Two auxiliaryelectrodes, a saturated calomel electrode (SCE) Luggincapillary with salt-bridge connection and a platinum netwere used as the reference electrode and counter elec-trode, respectively. In order to avoid the difference ofohmic drop during the electrochemical test, the speci-men, SCE salt bridge connection and platinum referenceelectrode were placed at fixed positions in the test cell.The electrolyte was 0.5 M H SOcontaining 0.05 M24KSCN.Before potentiodynamic polarization test, the solutionwas kept at room temperature and deaerated with nitro-gen gas at least 45 min. The specimen was sealed withacrylic resin and left an area of 1 cm exposed to the2solution during potentiodynamic polarization test. Acopper wire was spot-welded onto the backside of thespecimen for applying polarization potential. The poten-tiodynamic polarization scans were conducted from62W.-J. Chou et al. / Surface and Coatings Technology 167 (2003) 5967Fig. 3. Comparison of potentiodynamic polarization curves for dif-ferent series of specimens with scan rates: (a) 100; and (b) 600mVymin.Fig. 4. The variation of corrosion current density with scan rate.Fig. 5. The passive current density changes with scan rate for all seriesof specimens.y800 to 800 mV (SCE). Various scan rates wereintroduced, which were 10, 20, 50, 100 and 600 mVymin.After each potentiodynamic polarization test, the cor-rosion potential, E, and the corrosion current density,corrI, can be determined by Tafel plot w20x. The criticalcorrpassive current density, I, and the passive currentcritdensity, I , can be obtained from the potentiodynamicppolarization curve.The corrosion power Q is defined as the integrationof the current density by time within a certain range inthe active region of the potentiodynamic polarizationcurve from y400 to y250 mV.Qs j dta|where j is the active current density (Aycm ), t is the2atime (s), and Q is the corrosion power (Cycm ) w21x.2The corrosion power Q represents the extent of metalsubstrate dissolved into the electrolyte. Therefore, small-er value of corrosion power Q can be correlated tohigher corrosion resistance of the specimens. The surfacemorphology of the specimens after potentiodynamicpolarization test was observed using a scanning electronmicroscope (SEM).3. Results3.1. Characteristics of the deposited filmsThe single layer ZrNy304SS and bi-layer ZrNyZry304SS were all gold-colored, and the single layer Zry304SS had the same color of Zr metal. Fig. 1 shows the63W.-J. Chou et al. / Surface and Coatings Technology 167 (2003) 5967Fig. 6. Corrosion potential vs. scan rate for all specimens.Fig. 7. (a) The critical passive current density and (b) normalizedcritical passive current density with respect to scan rates.AFM topographic image of ZrN-coated specimen. Asmooth surface with roughness less than 5 nm wasobtained. The film surfaces look compact and contain afew defects observed by the SEM micrographs. Fromthe previous study w18x, both cross-sectional SEM andTEM images (figs. 1 and 6 in Chou et al. w18x) showedthat the ZrN films have a densely columnar structurewith an average column width of 50 nm. The NyZrratios, determined from XPS measurements, are essen-tially stoichiometric (NyZrs1) for all ZrN films, whichis consistent with our earlier research w18x. From theSIMS composition depth profiles, the film thickness ofeach coating can be determined as 600 nm. The com-positions are also uniformly distributed for each layerfrom the film surface to the 304 stainless steel substrate.The testing conditions of the specimens and results aresummarized in Table 1.3.2. Potentiodynamic polarizationFig. 2 shows the potentiodynamic polarization curvesfor bare 304 stainless steel, Zr, ZrN and ZrNyZr withvarious scan rates in solution 0.5 M H SO containing240.05 M KSCN, respectively. Table 1 lists the values ofEand Ifor all series of specimens obtaining fromcorrcorrthe Tafel plot and those of Iand I from the poten-cirtptiodynamic polarization curve. The potentiodynamicpolarization curves for a series of specimens are com-pared in Fig. 3(a,b) at two different scan rates, 100 and600 mVymin. From Table 1 and Fig. 3, apparently, thecorrosion current density decreases abruptly for coatedspecimens and the polarization curves can be dividedinto two groups: coated and uncoated specimens.Fig. 4 delineates that the bi-layer ZrNyZr coating,with the lowest I, exhibits the highest corrosioncorrresistance among the three coatings. Compared with thebare 304 stainless steel, the coated specimens providegood corrosion resistance and the corrosion rate decreas-es at least an order of magnitude for every scan rate.Figs. 4 and 5 also show that both corrosion currentdensity and passive current density increase with theincrease of polarization rate for bare 304 stainless steel,which is consistent with the results in the recent studiesw2224x. Mansfeld w25x pointed out that the trend forpassive current density with different scan rates shouldbe ignored, because this value is potential-dependent.However, the passive current density provides usefulkinetic information. The stability of the passive film canbe represented by the passive current density, i.e. largerI sless stable film. At higher scan rate, the anodicpreaction is increased and the film formed is less protec-tive; consequently larger corrosion current density andpassive current density are expected w26x. Fig. 5 depictsthe passive current density varying with scan rates forall series of specimens. It can be seen that in general64W.-J. Chou et al. / Surface and Coatings Technology 167 (2003) 5967Table 2Summary of corrosion current density Iand corrosion power QcritMaterialScan rateIcritNIcritQNQ(mVymin)(mAycm )2(Coulombycm )2304SS10198.158.1320167.765.1150138.062.26100144.851.14600127.750.16Zry304SS10191.820.972.900.3620195.541.172.030.405022.890.170.350.1610036.0260016.300.130.020.12ZrNy304SS1019.770.100.500.062010.260.060.340.07503.060.020.060.031003.850.030.040.046003.600.030.010.04ZrNyZry304SS1029.350.150.340.04205.030.030.050.01503.350.020.040.021002.380.020.020.026001.270.010.0010.01the passive current density increases with scan rate;especially for the bare stainless steel specimens, thepassive current densities show an increase of more than2 orders of magnitude as the scan rate increases from10 to 600 mVymin. On the other hand, for the coatedspecimens the increase of passive current density is lessdistinct and within one order of magnitude.Fig. 6 shows the results of corrosion potential withrespect to scan rate for all specimens. Similar to thecorrosion current density and passive current density,the Evalues are obviously divided into two groups,corrcoated and uncoated. The bare 304 stainless steel(approx. y450 mV) shows slightly lower corrosionpotential than other coated specimens (approx. y435mV). According to the precision tests, the deviation ofthe corrosion potential and corrosion current density inEG&G 263A were approximately 4 mV and 0.5 mAycm , respectively, for bare 304 stainless steel at the same2scan condition. Therefore the difference of EandcorrIvalues of the coated and uncoated specimens iscorrsignificant.The critical passive current density provides someuseful information. In previous studies w6,7,11x, thisvalue was used to evaluate the pinhole area of theceramic metal nitride film coated on metal substrate.The normalized critical current density (NI), NIscritcrit, is defined as an index for physicallyIfilmy304SS.critI304SS.critrepresenting the exposure area after potentiodynamicpolarization scan. Fig. 7(a,b) depict the critical passivecurrent density and normalized critical passive currentdensity varied with scan rate, respectively. Obviously,the pinhole rate of the ZrNyZr coating was lower thanthat of other two coatings.In general, the corrosion current density is influencedby many factors, such as temperature, surface condition,nitrogen purge rate, electrolyte concentration, etc. duringpotentiodynamic polarization test. It can be seen in Fig.4 that the trend of Ivalue is deviated at scan rate 10corrmVymin for ZrNyZr specimen. To clarify the phenom-enon, the corrosion power Q is introduced. The corrosionpower Q is the integrated electric charge per unit areaof the specimen during potentiodynamic polarizationtest w21x. This index, Q, directly represents the metalsubstrate dissolved through the pinhole to the electrolyte.The results of Q are listed in Table 2. Fig. 8(a) displaysthe results of Q for all series of specimens with respectto scan rate. It is found that the Q value decreases withthe increase of scan rate, and a linear trend is alsoobtained for bare 304 stainless steel. The data are a littlescattered for the coated specimens, but a similar rela-tionship still exists. From this figure, the bi-layer ZrNyZr specimens still shows higher corrosion resistancethan others.For the ceramic films coated on metal substrates, itis usually assumed that the ceramic films are immuneto corrosion. The metal substrate therefore plays adominant role in corrosion, while the corrosion in theceramic film can be ignored. Accordingly, the normal-ized critical current density NIrepresents the pinholecritrate of films coated on metal substrate and the ceramicfilms are immune of corrosion, and therefore the corro-sion power Q is closely related to the NIof the coatedcritspecimen. The relation between Q and NIis depictedcrit65W.-J. Chou et al. / Surface and Coatings Technology 167 (2003) 5967Fig. 8. (a) The corrosion power Q and (b) normalized corrosion pow-er NQ for all series of specimens vs. scan rate.Fig. 9. The corrosion power Q vs. normalized corrosion current den-sity NI.critFig. 10. The surface morphology of specimen ZrN film coated on 304stainless steel after potentiodynamic polarization tests with a scanningrate of 100 mVymin.in Fig. 9. It can be seen that the Q values increase withincreasing NI, and the data are within a narrow bandcritfor all series of specimens.Similar to the NI, a normalized corrosion powercritNQ, was established in this study.Q filmy304SS.NQsQ 304SS.The results of NQ for all specimens are summarized inTable 2. Fig. 8(b) further displays the results NQ withrespect to scan rate for the specimens coated with Zr,ZrN and ZrNyZr. The specimens with ZrNyZr coatingobvious show the highest corrosion resistance than thosewith Zr and ZrN coatings.Fig. 10 depicts the typical surface morphology ofspecimen coated with ZrN film after potentiodynamicpolarization scan with a scan rate of 100 mVymin. Thepicture shows a local delamination of ZrN film due tocorrosion test and there is no apparent corrosion phe-nomenon on the remaining film surface. Generally, thecorrosion medium penetrates the film through somelocal defects and eventually leads to the delaminationof the film. In Fig. 10, the serious intergranular corrosionof the stainless steel substrate is observed. The grainboundaries of the metal substrate can be easily seen.These results confirm the above statement that theceramic thin films are immune from corrosion, and thecorrosion phenomenon occurs on the metal substrateduring the corrosion process.4. DiscussionThe ceramic films coated on metal substrate arecommonly believed to be immune from corrosion. FromFig. 10, it can be seen that the film surface does not66W.-J. Chou et al. / Surface and Coatings Technology 167 (2003) 5967exhibit apparent difference before and after potentiod-ynamic polarization scan. In contrast, the exposed metalsubstrate is seriously attacked intergranularly. However,if the ceramic film is absolutely immune from corrosion,the corrosion potential of the coated specimen must bethe same as that of the bare stainless steel. Actually, asshown in Fig. 6, the corrosion potentials are dividedinto two groups: the coated and uncoated specimens.This phenomenon can be explained by galvanic corro-sion. The ceramic-film coated metal substrate can beconsidered as a galvanic couple. In the specimen, ZrNhas a higher corrosion potential (50 mV vs. SCE) w3xand the major exposure area with electrolyte; on thecontrary, the 304 stainless steel substrate has a lowercorrosion potential (y450 mV) and the minor exposurearea through the pinhole. This combination fulfills thebasic requirement of the typical cathodic control ofgalvanic corrosion. Therefore, the coated specimenshave a slightly higher corrosion potential than the baremetal substrate.The evidence of pitting corrosion can further supportthe above argument. It is clear that from the polarizationcurves shown in Fig. 2, the passive current is unstablefor the coated specimens. The scatter of the currentdensity in the passive region can be explained by theclogging of the corrosion product in the pinholes w3xand the breaking down of the films on coated specimens.The present study shows that the bi-layer or multi-player coating may enhance the corrosion resistance ofthe specimens. In Figs. 4 and 5, compared with the baresubstrate, the Iand Idecreases at least 1 order ofcorrpmagnitude for the bi-layer specimens, and the bi-layerZrNyZr coating exhibits the highest corrosion resistanceof all coated specimens. Since corrosion occurs via thediffusion of the electrolyte through pinholes and attack-ing the underneath substrate, the pinhole number andsize are closely related to the corrosion resistance ofspecimens. The index NIis introduced to representcritthe exposure area of the coating. In Fig. 9, the ZrNyZrbi-layer coating shows the lowest NIvalue for allcritscan rates. The corrosion power Q increases with theincrease of the exposure area of coatings, NI, ascritshown in Fig. 8(b), which further supports the pinholecorrosion mechanism. It also suggests that bi-layercoating may interrupt the pinhole connection throughthe coating surface to the underneath of metal substrate,minimize the exposure area, and thereby improved thecorrosion resistance.The changing scan rate in this study was designed forrevealing the kinetic dependence of corrosion parame-ters. As mentioned earlier, the increase of scan rateleads to the increase of anodic reaction, and the oxidefilm formed on the metal surface is less protective.Therefore, the trends of Iand I with respect to thecorrpscan rate, as shown in Figs. 4 and 5, respectively, canprovide kinetic information for both coated and bare304 stainless steel specimens. Fig. 4 demonstrates thatIincreases with scan rate for bare 304 stainless steelcorrbut not as obvious in the other three coated specimens.Since the exposure area of the substrate metal in thecoated specimens is much smaller than that in baremetal specimen, the effect of increasing anodic reactionis not as effective as that for bare 304 stainless steel. Inaddition, since the pinhole rate is different in the threecoatings, the corrosion current densities are different.On the other hand, I in Fig. 5 shows the stability ofpthe oxide film, and therefore the oxide film stabilitybetween the coated specimens is not significant. Again,due to the small exposure area of the substrate metal,the effect of changing scan rate on the oxide filmstability in coated specimens is much less than that onbare 304 stainless steel specimens.5. ConclusionThe corrosion resistance of Zr, ZrN and ZrNyZr filmsdeposited on 304 stainless steel was investigated usingpotentiodynamic polarization tests with varying scanrates. The bi-layer ZrNyZr coating exhibits the highestcorrosion resistance compared to the other two singlelayer
- 温馨提示:
1: 本站所有资源如无特殊说明，都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
2: 本站的文档不包含任何第三方提供的附件图纸等，如果需要附件，请联系上传者。文件的所有权益归上传用户所有。
3.本站RAR压缩包中若带图纸，网页内容里面会有图纸预览，若没有图纸预览就没有图纸。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 人人文库网仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对用户上传分享的文档内容本身不做任何修改或编辑，并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容，请与我们联系，我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
人人文库网所有资源均是用户自行上传分享，仅供网友学习交流，未经上传用户书面授权，请勿作他用。
|
2:不支持迅雷下载,请使用浏览器下载
3:不支持QQ浏览器下载,请用其他浏览器
4:下载后的文档和图纸-无水印
5:文档经过压缩，下载后原文更清晰
|
川公网安备: 51019002004831号