共查询到20条相似文献,搜索用时 93 毫秒
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针对某厂在以DX53D+Z镀锌板作为结构件进行冲压成形过程中发生的表面橘皮缺陷,采用金相显微镜、扫描电镜、能谱仪等设备对材料的宏观形貌、金相组织、显微形貌、力学性能等进行综合分析,从而探索出其橘皮缺陷的产生原因。结果表明:造成该批冷轧退火镀锌板产生橘皮缺陷的原因为铁素体晶粒出现混晶,晶粒明显大小不一,拉延时,混晶中大小晶粒变形彼此不协调,变形不够均匀,容易从粗大铁素体晶粒变形晶界处起裂,形成鱼鳞状分布、凹凸不平的粗糙表面缺陷即橘皮缺陷。 相似文献
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针对X52热轧带钢出现的表面条状翘皮、发裂缺陷,利用金相显微镜和扫描电镜分析等方法,结合生产实践对缺陷的宏、微观形貌特征、缺陷部位、钢的冶金质量的变化等方面进行研究分析,进而区分缺陷形成的原因,并提出解决对策。 相似文献
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利用扫描电镜和金相显微镜对一种弹簧钢丝断口进行了检测,包括钢丝断口和钢丝表面的麻点、横向缺陷和纵向条状缺陷。结果表明:表面麻点为氧化铁皮残留压入所致,横向及纵向缺陷均在热态下产生,三类缺陷均不会导致钢丝发生断裂。钢丝表面凹凸不平呈解理状,断裂区域未观察到明显冶金缺陷,其断裂是淬火内应力加组织应力过大所造成的。 相似文献
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Vitreous coatings are widely used for protecting steel at temperatures up to 600 °C in applications where high oxidation- and wear-resistance are required. However, the action of alkaline chemical agents such as household cleaning products can cause the devitrification and spalling of these coatings, with the consequent loss of their protective properties. In such cases, corrosion of the substrate is accelerated due to the heat treatment applied during the manufacturing process of the coating — tempering or curing. The present work characterizes the initial stages of this deterioration using the electrochemical noise technique (EN). When coatings are undamaged the current noise is very low, with current intensity values of the order of picoamperes. However, when defects appear as a result of chemical attack, the systems electrical activity changes considerably and there is an increase in both current and potential noise. This work also establishes the loss of the coatings protective nature as a function of spectral noise resistance, Rsn, finding good concordance with values obtained by other more conventional techniques such as electrochemical impedance. 相似文献
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The oxidation behavior of Ni-Cr-Al-Y coating produced by multi-arc ion plating with and without an enamel coating was investigated in flow oxygen and oxygen containing water vapor at 900 ℃. The results show that Ni-Cr-Al-Y coating exhibits low oxidation rate at 900 ℃ in pure oxygen and the oxidation kinetics follow the parabolic rate law. The presence of water vapor accelerates the oxidation rate of Ni-Cr-Al-Y coating and K38G alloy.The enamel top coating is very effective in protecting the Ni-Cr-Al-Y coating from water vapor corrosion attack, but the corrosion attack beneath the enamel coating is not observed. 相似文献
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Yuming Xiong Chunhong Guan Shenglong Zhu Fuhui Wang 《Journal of Materials Engineering and Performance》2006,15(5):564-569
The effect of enamel coating on the isothermal and cyclic oxidation at 900 °C in air and on the hot corrosion resistance of
Ti-24Al-14Nb-3V in both 85% Na2SO4+15%K2SO4 and 15%NaCl+85% Na2SO4 molten mixed salts at 850 °C was investigated. The results indicated that Ti-24Al-14Nb-3V alloy exhibited poor oxidation
resistance due to the formation of nonprotective Al2O3+TiO2+AlNbO4 scales and poor hot corrosion resistance due to the spallation of scales formed in molten Na2SO4+K2SO4 and NaCl+Na2SO4. Enamel coating suppressed the migration of oxygen and corrosive ions into the substrate to improve the oxidation and hot
corrosion resistance of Ti-24Al-14Nb-3V alloy. However, the dissolution of oxides components of the coating into the molten
salts degraded enamel coating and the degradation of the coating involved a process by which Cl− anion penetrated into the substrate through voids in the coating to accelerate corrosion of Ti-24Al-14Nb-3V alloy. 相似文献
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The effect of enamel coating on long-term isothermal oxidation at 700 ℃ and cyclic oxidation at 800 ℃ in air and hot corrosion resistance of Ti-24Al-17Nb-0. 5Mo in 75% (Na2SO4 K2SO4 ) 25% NaCl (mass fraction) molten mixed salts at 700 ℃ was investigated. The results indicate that Ti-24Al-17Nb-0.5Mo alloy exhibits relatively poor long-term oxidation resistance due to the formation of Al2O3 TiO2 Nb2O5 mixed scales and poor hot corrosion resistance due to the spallation of scales formed in molten (Ns, K)2 SO4 NaCl. Enamel coating can effectively protect Ti-24Al-17Nb-0.5Mo alloy from long-term oxidation at high temperature in air and remarkably improve the hot corrosion resistance of Ti-24Al-17Nb-0. 5Mo alloy, and can act as the barrier to suppress the migration of oxygen and corrosive ions into the substrate. 相似文献
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Cr25Ni20Si2合金表面复合搪瓷涂层的抗热腐蚀研究 总被引:1,自引:0,他引:1
在Cr25Ni20Si2合金上制备了施加Ni中间层的复合搪瓷涂层,研究了Cr25Ni20Si2合金、搪瓷涂层及含镍中间层的复合搪瓷涂层在800℃熔融盐(75%Na2SO4+25%NaCl)下的腐蚀行为和腐蚀机理。试验表明合金在孕育期结束后发生灾难性腐蚀,腐蚀机理主要遵从硫化-碱融模式;未镀镍搪瓷涂层主要以直接脱落丧失保护能力,复合搪瓷涂层则以物理减薄方式缓慢失效。搪瓷涂层使合金的抗热腐蚀能力提高了30%,复合搪瓷涂层可使合金抗热腐蚀能力提高100%以上。这种复合搪瓷涂层是有效的抗热腐蚀涂层。 相似文献
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