共查询到20条相似文献,搜索用时 46 毫秒
1.
一种特殊要求,需在φ12mm不锈钢1Cr18NiqTi球上电镀0.4mm厚度的硬铬镀层.由于采用挂镀,于是就提出下列问题:1如何保证镀层与基体的结合力.2 如何保证椭圆度和挂具遮挡不影响质量. 不锈钢基体与硬铬间的结合力是可以解决的.加强前处理,去油,去氧化膜,充分阴极活化.使阴极释放的原子态氢充分还原不锈钢表面的氧化膜,再进行电镀,镀层质量就可以得到保证.但是,镀铬挂具遮挡的那个部位,镀层薄或者镀不上;无论怎样注重电力线均匀分布,也易产生椭圆度.我们是这样分析它:为使挂具遮挡处镀层厚度与其它部分不至相差太多,也为使钢球电镀不产生质量 相似文献
2.
3.
4.
5.
6.
先通过酸蚀去除钛合金表面的氧化膜,再由二次浸锌使TC4钛合金表面形成一层均匀致密的锌,最后进行化学镀镍.通过金相显微镜、扫描电镜对主要工艺阶段中基体表面形貌进行表征,利用能谱仪对施镀后的基体表面成分进行分析,采用热震法检测镀层的结合力,并通过摩擦磨损试验机和显微硬度计分别测得镀层的表面摩擦因数及显微硬度.采用正交试验优化了几项工艺参数:首次浸锌时间90 s,二次浸锌时间120 s,镀液温度85°C,pH 4.5.使用最优工艺所得镀镍层组织致密,表面均匀光洁,摩擦因数在0.25~0.30之间,显微硬度为593.7 HV,经5次循环的热震实验后,镀层表面保持完整,无开裂、剥落现象,表明其具有优异的减摩性、较高的显微硬度且结合力良好. 相似文献
7.
烧结型NdFeB永磁体的镀前处理工艺 总被引:3,自引:0,他引:3
对NdFeB永磁体材料的不同前处理工艺流程和工艺规范进行实验,并对不同前处理工艺的镀层结合力和耐蚀性进行测定。结果表明,经打磨、封孔、抛光、化学除油、除锈、活化等前处理的试片可直接电镀、经划痕试验和锉刀试验,镀层与基体的结合力良好,并经盐雾试验检测其耐蚀性优良。 相似文献
8.
9.
先通过酸性锌镍合金电镀工艺在钢铁基体或锌合金基体表面电镀锌镍合金,以代替传统的氰化物镀铜底层和氰化物镀黄铜锡中间镀层,然后电镀白铜锡。这种镀层结构在热震试验后没有出现镀层起泡和脱落,在中性盐雾试验24 h内没有红锈生成,具有较高的结合力和耐蚀性。 相似文献
10.
11.
我厂3号回转窑(Φ4m×60m)生产线在1996年年底由SP窑(产量912t/d)改为NSP窑(产量1320t/d),预分解系统为四级旋风预热器带离线式分解炉 相似文献
12.
13.
14.
乙烯酮(双乙烯酮)是十分重要的化工中间体,其下游产品较多。江苏某化工厂开发生产乙烯酮(双乙烯酮)下游产品三十多个,年生产规模三万多吨,是国内以乙烯酮(双乙烯酮)为中间体生产精细化学品的综合骨干企业。针对乙烯酮(双乙烯酮)下游产品废水特点,该厂结合企业实际,开展了产品优化,结构调整,清洁生产,资源循环利用,节水降耗等工作,从源头削减了污染物的生产。同时投资二千多万元新建预处理装置三套,6000m3/d废水生化处理装置一套,使全厂乙烯酮(双乙烯酮)下游产品的废水得到了有效的治理。 相似文献
15.
16.
17.
The objective of the study was to explore the effect of the degree of deacetylation (DD) of the chitosan used on the degradation rate and rate constant during ultrasonic degradation. Chitin was extracted from red shrimp process waste. Four different DD chitosans were prepared from chitin by alkali deacetylation. Those chitosans were degraded by ultrasonic radiation to different molecular weights. Changes of the molecular weight were determined by light scattering, and data of molecular weight changes were used to calculate the degradation rate and rate constant. The results were as follows: The molecular weight of chitosans decreased with an increasing ultrasonication time. The curves of the molecular weight versus the ultrasonication time were broken at 1‐h treatment. The degradation rate and rate constant of sonolysis decreased with an increasing ultrasonication time. This may be because the chances of being attacked by the cavitation energy increased with an increasing molecular weight species and may be because smaller molecular weight species have shorter relaxation times and, thus, can alleviate the sonication stress easier. However, the degradation rate and rate constant of sonolysis increased with an increasing DD of the chitosan used. This may be because the flexibilitier molecules of higher DD chitosans are more susceptible to the shear force of elongation flow generated by the cavitation field or due to the bond energy difference of acetamido and β‐1,4‐glucoside linkage or hydrogen bonds. Breakage of the β‐1,4‐glucoside linkage will result in lower molecular weight and an increasing reaction rate and rate constant. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3526–3531, 2003 相似文献
18.
Conclusions It is significant that the purification on a single passage of viscose through porous ceramic corresponds to the result of a two-stage filtration of it in industrial filter-presses with standard fillings.Kiev Combine. Kiev Technological Institute of Light Industry. Translated from Khimicheskie Volokna, No. 3, pp. 20–22, May–June, 1969. 相似文献
19.
A refined nonlinear value of the main parameter of a material, i.e., the elongation modulus versus the instant temperature value, was suggested for introduction into the computational algorithm of tempering stresses. 相似文献
20.