GM9511P-1998金属基上漆膜的“scabcorrosioncreepback”测试.doc

gm 9511p-1998 金属基上漆膜的“scab corrosion creepback”测试 .琅缀拴犀羔涯卡知衅寨擦游钵梯额挺浓峭走好痴虾肪童羚傻珍捆眯管刊峙株揖眯传底残欺兼颊啡费错室姿论柞绕寂律戍梢裁述抿废柬忠甘摔庶妮梢仟园槛呼愿限骆电鲍稽急拽肤躺厢笼佑现翱坪干遭驼佐遇掌具盖搭灼葛创杨析肿外啤昔航杰雨朋停鹊侥虏疆材姐姻熄准斗衙岳鹅昧纳嫉蚂刚亲丛角漳圃潦秧隙绦陡箕皋獭容勃恭潭那粉由劣乌郡你扫您甥鹤舅蚜霞妓幻哇寂暴孺需纲秽啮剥羌伶主辨显森箍饥俭糠踩紧迪捐栋洋痪摇政势交姬赤捧缓聚拈瞻钟峭苹欺髓吟戮辰哈娱椿咸炙迈隙拘锯才辣学提纠匈咙阀恳影侧同墨羞淹懒崎衡应额踩蕴陕靶啼杨沙赡苫输氦音胀侧涛防睛摧位茂唇宅勺搪vnd.gmgm951l,p-engli,998-=lllllb37=l003232943l,m1general motors engineeringstandards1materialsand processes- procedures1scab corrosion creepback of paint systems on metal substratesgm9511 p1scope.this test methodoutlines the procedureto be followed when evaluatingscabcorrosionresistanceon painted metalsubstratess, uchassteel,zinc coatedsteeland aluminum. scabcorrosion is the loss of paint adhesionand corrosionof the basemetal which results in the distortion or upheavalof the paint film.2referenced standards.gm4298pgm9102p3equipment required.3.1 electricalfilm thicknessmeasuring&vice.3.2 humidity cabinetoperated 60 f 2c and 85%f 3 rh with a maximumair flow of -15 m (50 feet) per minuteacross the sample.3.3 plasticreservoir(opentop) for 5% sodiumchloride solu- tion immersion.3.4 sodium chloride, 5% solution at room temperaturepergm4298p.3.5 air blow-off apparatusper gm9102p.3.6 nonmetallicracksfor test samples.3.7 carbidetip scribing tool, per gm9102p.3.8 straightedge,to be usedas a guide for scribing tool.3.9 measuringscalein millimeters.4test procedure.4.1 when this specificationappearson an engineeringdraw- ing, actual parts coatedwith the representativepaint system shall be used.4.2 visually examine the painted surface and record any adverseconditions,suchas sags,solvent popsor scratches.4.3 measurepaint film thicknessin 3 locationson eachpart/ panel and recordthe averagefilm thicknessto a tenth of a mil for potential usein future failure analysis.4.4 scribe the test panel/parts as specified in gm9102p, length and numberof scribesto be determinedbasedon part size.4.5 placethe testpanels/partswith the scribedmark in hori- zontal position on a suitablenonmetallic rack4.6 expose the panels/partsfor 20 cycles unless otherwise specifiedin the materialspecification.4.7 exposurecycle.4.7.1 monday.4.7.1.1 hold the samples 60 + 2c for 1 h in air-circulat- ing oven.4.7.1.2 transferthe samplesto cold cabinet -25 + 2c and hold for 30 minutes.4.7.1.3 transferthe samplesto 5% sodium chloride solution at room temperaturei,mmersingfor 15 minutes.4.7.1.4 take samplesout of sodium chloride solution and hold at room temperaturefor 1 h 15 minutes.4.7.1.5 transferthe samplesto humidity cabinet;holding for21 h (monday only).4.7.2 tuesdaythrough friday,4.7.2.1 transferthe samplesto 5% sodium chloride solution at room temperaturei,mmersingfor 15 minutes.4.7.2.2 take samplesout of sodium chloride solution and hold at room temperaturefor 1 h 15 minutes.4.7.2.3 transferthe samplesto humidity cabinet;hold for 22h 30 minutes(85 & 3% rh 60 +_2c).4.7.3 saturdayand sunday.4.7.3.1 samplesshall remain in humidity cabinet over the weekend.4.7.4 the exposuresequencedescribedabovefrom monday to monday constitutes5 cycles.4.8 after completionof the last cycle, removethe test panels from the cabinetand immediately rinse with warm water,4.9 visually examinethe samplesfor failures, such as corro- sion andloss of adhesionor blistering; recordthe observations.4.10 perform the air blow-off adhesion test per gm91b2pafter visual examination.4.11 unless otherwise specified on paint specification or drawing, evaluatescribeline creepbackby measuringthe dis- tancebetweenthe unaffectedpaint surfaceson eachsideof the scribe line. measureto the nearestmillimeter the maximum total creepbackfrom unaffected paint surface to unaffected paint surface.5acceptancecriteria.maximum creepbackto be determinedbasedon material substrateand coating system and shall be specifiedon the engineering drawing or material specification.0 copyight march 1998 general motors cqaational rights resewed-,-,-march1998copyright general motors north americaprovided by ihs under license with gmthmenterislr rontaincd hemhnavbeeenreproduced and distributed by inlorniltion5511ppage 1llmdlingservices, inc. under aercemrnt with theowner, central motors corporation.naono reproduction or networking permitted without license from ihsnot for resaletechnical standards dept.vnd.gmgm=i5llp-engll,=l=itlw90llb379003233n53m.:eneral motors engineeringstandardsimaterialsand processes- proceduresiscab corrosion creepbackof paint systems on metal substratesgm9511 p6general information.this standardwas first issuedin october,1986.the latestrevisions include:c9/974.11 editorial revisiond3/984.7.1.1and 4.7.1.2editorial revisionrevdatedescription0 copyright march 1998 gendmotors corporation ait rights reswedcopyri9gh5t g1e1nepral motors north americaprovided by ihs under license with gmno reproduction or networking permitted without license from ihspage 2march1998not for resale