共查询到19条相似文献,搜索用时 62 毫秒
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一、概述铸铁管件一般采用可锻铸铁(俗称玛钢)制作,其材料成分为碳约3%,硅约1%,其他元素<10%.在翻砂制作过程中,零件表面往往存在少量灰砂、气孔等缺陷,基体也较为粗糙.传统的工艺是采用热镀锌.但耗锌量大,消耗能源多.成本也较高.因此,为数甚多的厂家已转向电镀锌.由于基体较粗糙,浸蚀以后,碳、硅裸露于表面,使氢的过电位降低,开始电镀时析氢严重,镀层难以沉积.管内壁沉积镀层更难.挂镀锌尚易解决,滚镀锌就存在较大的难度了.青岛市某厂采用滚镀工艺加工铸铁管件,每桶电流开至近400安培,滚镀时间长至近2小时,但上镀还是很慢.特别是管件内壁镀层发暗、粗糙,甚至无镀层. 相似文献
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高强度螺栓的表面处理与机械镀锌 总被引:2,自引:0,他引:2
介绍了高强度螺栓电镀锌工艺中,对氢脆的控制情况,以及适于标准件行业的消除氢脆失效的表面处理新方法-机械镀锌。这种方法为我国高强度标准的镀锌开辟了一条新的途径,能提高我国高强度标准件的市场竞争力,是一种表面处理的先进工艺。 相似文献
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根据铸铁密封环的表面磨损形式,提出采用复合刷镀技术可有效修复和强化铸铁密封环的配合面。采用高堆积碱铜作尺寸层,刷镀层做工作层。介绍了复合刷镀工艺流程与刷镀液组成(270g/LNiSO4.6H2O,60g/LNiCl2.6H2O,50~60mL/LH3PO3,66g/L柠檬酸三钠,35g/LH3BO3,15g/L纳米Al2O3,微量表面活性剂,pH4.5)。提出工艺操作的几点注意事项。经测试表明,该复合刷镀工艺简单,镀层表面晶粒细密,硬度高(平均硬度为596HV),耐磨性好,提高了铸铁密封环的使用寿命。 相似文献
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Jin‐Hong Fan Hong‐Wu Wang De‐Li Wu Zhi‐Gang Liu Lu‐Ming Ma 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2011,86(10):1295-1302
BACKGROUND: Little attention has been paid to the use of large‐sized scrap cast iron for reduction of refractory organic pollutants at neutral pH and in the presence of dissolved oxygen (DO). RESULTS: Scrap cast iron and copper‐modified cast iron with fresh surfaces have a high reactivity towards the reduction of 2,4‐dinitrotoluene (2,4‐DNT). The extent of conversion reached around 80% and 97% respectively, though it gradually decreased with repeated reactions to relatively stable values of 63% and 72%, and recovered once the reacted filings were cleaned by dilute acid. After 50 days reaction, no dissolved copper appeared in the copper‐modified cast iron process. The mass loss of copper due to physical detachment reached 1.1% of the total coated copper within the initial 20 reaction days, and only 0.3% appeared in the next 30 days. 2,4‐DNT oxidizes scrap cast iron to generate mainly FeFe2O4 with DO, however, it oxidizes scrap copper‐modified cast iron to generate mainly γ‐FeO(OH) and α‐FeO(OH). CONCLUSION: Both samples of cast iron were successfully applied in the treatment of neutral wastewater containing 2,4‐DNT with high reactivity and good repeatable efficiency. Electrode reaction rate was enhanced by the deposited copper, which has strong chemical and physical stability. Copyright © 2011 Society of Chemical Industry 相似文献