利用SEM和电化学交流阻抗分析方法对彩涂家电板局部起泡腐蚀失效行为进行了分析,阐述了腐蚀失效产生的原因及过程,提出了针对该腐蚀失效问题的改进建议.

The coil collapse of prepainted sheets during production and package may cause some troubles.The primary reasons of coil collapse during curling were analyzed theoretically in the paper.The coil collapse of prepainted sheets was mainly caused by lower friction between steel sheets.The maximum static friction coefficient of different sorts of prepainted sheets were measured.The causes of the coil collapse because of different sorts of coatings were analyzed in microstructure.Finally,the counter measures to prevent coil collapse during production were suggested.

With regard to the degradation of the corrosion resistance of a colour coated steel sheet due to the paint film peeling after it is profiled,the investigations on the reasons of degradation are analyzed.And thus the steel sheet with the defect of paint film peeling is inspected by scanning electron microscope,energy dispersion spectrometry and salt spray corrosion test.The inspected results show that the reason why the corrosion resistance of the colour coated steel sheet is degraded due to its defect of paint peeling is that the sheet is short of passivating pretreatment.However the thickness drop of the coating layer of the colour coated steel sheet is also one of the reasons.

通过测量不同固含量涂层彩涂板在不同浸泡时间条件下的电化学阻抗谱,研究了涂层固含量对彩涂板耐蚀性能的影响。结果表明,涂料中固含量为55%时,彩涂板耐蚀性能最好。

The surface morphology, chemical composition and corrosion resistance of the prepainted sheets with coating peeling were tested by SEM, EDS, EIS and NSST (Neutral Salt Spray Test). The cause of coating peeling and its influence on corrosion resistance of prepainted sheets were analyzed by contract testing. The improving measure was proposed to improve the machining property and corrosion resistance of the prepainted sheets.

The causes leading to the defects of blasting holes formed on the surface of an aluminum-zinc coated steel sheet during production are analyzed,and thus it is confirmed that the blasting hole defects are mainly caused by such factors as different chemical characteristics on the part of the aluminum-zinc alloy coating,different thermophysical properties and defects of the aluminum-zinc alloy coating.Based on the said analysis,the defects of blasting holes occurred on the surface of the aluminum-zinc coated steel sheet can be avoided by taking such measures as improving the surface quality of the aluminum-zinc alloy coating and roughness of skin passed rolls,decreasing the defects of porinesses or pores formed on the surface of the aluminum-zinc coated sheet as well as improving the curing temperature curves of the coated steel sheet,and as a result the coated steel sheet can meet the quality requirements demanded by consumers.

Dynamic CCT curves and microstructure evolution of 42CrMo steel were detected by dilatometry and metallography and hardness test.The results show that at low cooling rate,the microstructure of 42CrMo steel mainly consists of ferrite,pearlite and bainite.With increasing of cooling rate(in the range of 0.2-1 ℃/s),the ferrite and pearlite reduce gradually until the microstructure mainly composed of bainite at the cooling rate of 1 ℃/s.As the cooling rate ≥3 ℃/s,martensite starts to form and until the martensite completely formed at the cooling rate ≥10 ℃/s.The high cooling rate and deformation is proposed to be responsible for the formation of martensite.

本研究的目的是通过分析颗粒涂料彩板的表面状态与表面微观形貌表征参数RPc值和Ra值之间的关系,建立颗粒涂料彩板的表面状态的量化指标,实验结果表明:表面粗糙度的RPc值和Ra值与颗粒涂料彩板的表面状态有着必然的联系,可以用做表面质量的约束指标;玻璃微珠的添加量和面漆膜厚对颗粒涂料彩板的机械性能和表面状态有着显著的影响,可作为工艺参数制定时的参考。

Through the analysis of surface morphology and chemical composition of the coatings and the base sheet of high gloss household appliances sheet by using SEM and electrochemical test,it was found that the surface gloss reduction of prepainted sheets for household appliances was caused by the local oxidized layer on base shect before painted.The results of salt spray test showed that the surface gloss reduction could affect the anti-corrosion property seriously,and the improvement methods to reduce the oxidation on the base sheet were given.

The corrosion behavior of a weathering steel 09CuPCrNi-A and a common steel F500L-Z in 3.5%NaCl solution was investigated by open circuit potential and electrochemical impedance spectrum（EIS） measurements.The results showed that the resistance of the steels increased first and then decreased with increasing soak time and tended to be steady after 1272 h. Bode charts indicated that the curves moved to low frequency and phase angle curves decreased gradually.Corrosion resistance of 09CuPCrNi-A was better than that of F500L-Z.

The corrosion resistance of Q420qD Ultra-low carbon bainitic high strength steel for bridge and FSOOL-Z steel was studied by means of neutral salt spray test and electrochemical measurement. The re-suits shown that corrosion resistance of Q420qD steel was better than that of F5OOL-Z steel by comparative neutral salt spray tests for 1440 h. The fact was also proved that corrosion resistance of Q420qD steel was better than that of FS00L-Z steel by electrochemical tests for different times in the neutral media in terms of their-free corrosion potentials, linear polarization curves and the electrochemical impedance spectrosco-py(EIS). Furthermore,electrochemical impedance for Q420qD steel increased with the immersion time, which illuminated that the rust layer of which was also getting thicker with immersion time. So a thicker and compact rust layer on its surface may become a good barrier to the corrosive spices from the electro-lyte so that to suppress the corrosion of steel substrate.

In this paper,the influencing factors on corrosion resistance of two kinds of phosphorized steel sheets A and B for household appliances were analyzed by ICP, metallography, electrochemical measure-ments and waviness-meter. The results show that the corrosion resistance of the phosphorized steel sheet can be enhanced by reducing the content of C, Si element and carbide in the sheet substrate and increas-ing the surface roughness of the sheet. The corrosion resistance of zinc-phosphate coating is better than i-ron-phosphate coating.

Anti-corrosion and mechanical properties are two very important properties of prepainted sheets for household appliances,which can affect the service life of household appliances significantly.Anti-corrosion & mechanical properties of prepainted sheets for household appliances were analyzed by selecting 3 factors,including passivation pretreatment,PMT and the film thickness through the orthogonal experiment,and the significance,which were analyzed by using ANOVA.It was found that choosing the proper pretreatment technology was the main solution of improving the relevant properties of prepainted sheets for household appliances.

By using scanning electron microscopy,glow discharge optical emission spectrometry,anodic polarization and neutral salt spray testing,the surface morphology,composition and corrosion resistance of new environmental friendly passivation hot galvanized steel was analyzed.The results indicated that the new environmental friendly passivation solution satisfied the ROHS standard.By adding plugging solvent,the corrosion resistance of new environmental friendly passivation galvanized steel was better than that of traditional hot hexavalent chrome passivation galvanized steel.

The microstructure and corrosion resistance of two types of new environmental protection passivating films for galvanizing coat were studied with SEM,glow discharge optical emission spectrometry,electrochemical protection measurement,NSS test and damp heat test.The results show that corrosion resistance of A environmental passivating films for galvanizating coat is obviously better than that of traditional hexavalent chrome passivating films,and B environmental protection passivating films for galvanizing coat is appreciably worse than that of traditional hexavalent chrome passivating films.The reason of A environmental protection passivating films with excellent corrosion resistance was discussed.

The mechanical property,scratch resistance,salt fog property and UV resistance of the coatings of precoated steel sheet used for refrigeration container were tested and measured.The general properties of four different kinds of resins such as polyvinylidene fluoride,silicone modified polyester,high durable polyester and conventional polyester were evaluated and discussed in the article.The test results showed that the high durable polyester provided better properties and lower cost,which can meet all requirements of coating property of precoated steel sheet used for refrigeration containers.

The influence of PMT and coatings film thickness on surface gloss and color difference of PVDF precoated sheets has been analyzed through the tests in this article.The test results showed that the coatings film thickness had much effect on the gloss than PMT.As a whole,the gloss increased as the coatings film thickness became higher and PMT lower.Less gloss changes caused by the coatings film thickness for the bright color coatings than that of dark coatings.PMT and the coatings film thickness showed greater effects on the value L than the value a and b.

Contents of Cr(Ⅵ) in the chromate conversion film on the surface of galvanized steel sheets were determined by ICP-AES and spectrophotometry.It was found that the presence of zinc sulfate showed significant effect on the values of content of chromium determined,which were inversely proportional to the amounts of zinc sulfate present.It was found that linear relationship between the values of Yt/s and X(the amounts of zinc sulfate present) was found as shown by the linear regression equation: Yt/s=98.809 88=0.233 42 X where Yt/s are the ratio of values of Cr(Ⅵ) found to be the respective values of standard ZnSO4(count with Zn2+) solution added.As proved by experimental tests,the interference of ZnSO4 on the determination of Cr(Ⅵ) was effectively eliminated by removing the Zn2+ ion by precipitation with sodium carbonate.

In this paper, the influencing factors on corrosion resistance of two kinds of phosphating household appliances sheets A and B were analyzed by ICP, metallurgical microscope, electrochemical measurement system and waviness-meter. The results show that the corrosion resistance of the phosphating household appliances sheet can be increased by reducing the content of C, Si element and carbide in the base sheet and increasing the surface roughness of the sheet. The corrosion resistance of zinc phosphate coating is better than iron phosphate coating. The corrosion resistance of the household appliances sheet remains good after phosphating. It was estimated through the electrochemical test result.

The properties of the two kinds of domestic appliance sheets A and B,including chemical component,metallographic structure,the surface status of surface activity and roughness etc.are tested and observed by devices,such as ICP,SEM,metallographic microscopic,electrochemical measurement system and waviness-meter and so on.The influence of surface status of the domestic appliance sheet on phosphatizing effect are analyzed.The results show that the uniform and dense phosphatizing coat can be hardly formed due to increasing carbide in the base plate of the domestic applicant sheet with increase of C and Si contents,the high surface activity of the domestic appliance sheet can make the phosphatizing coat bluing easily,and it is favorable for forming the uniform and dense phosphatizing coat by increasing the surface roughness of the domestic appliance sheet.