硬化工艺对双辉渗银不锈钢膜层结构及性能的影响

不锈钢双辉渗银处理获得的渗银层硬度较低且不耐磨,因此设计硬化方案对渗银不锈钢进行硬化,以改善其耐磨性。采用等离子氮碳共渗技术进行渗银层的改性工作,对不同工艺下膜层的微观形貌、成分及物相构成进行了分析,并对比了其硬度及磨损性能。两种硬化工艺下测得的硬度及磨损试验数据如下:渗银处理(×3h)+渗氮碳处理(×10h)工艺制备的试样表面硬度值为283HV0.025,15s,平均摩擦系数为0.4287,磨损失重为12.9mg;渗氮碳处理(×10h)+渗银处理(×3h)工艺制备的硬度值为544HV0.025,15s,平均摩擦系数为0.4266,磨损失重为11.5mg。可以看出渗银处理(×3h)+渗氮碳处理(×10h)工艺未提升渗银不锈钢的表面硬度,渗氮碳处理(×10h)+渗银处理(×3h)工艺将渗银不锈钢的表面硬度提升了近1倍。两种硬化工艺对渗银不锈钢的耐磨性能略有改善。     

3Cr2W8V钢稀土硼铝共渗工艺和性能研究

研究了3Cr2W8V钢稀土硼铝共渗工艺,渗层组织和性能.结果表明,采用文中所述共渗工艺,可在模具的工作带上形成一层高性能的共渗层,渗层表面硬度可达1800～2000HV,取得良好效果.     

N等离子体基注渗方法研究

等离子体基注渗技术在材料表面改性中具有极为重要的应用，本文报道了一种实现恒温条件的N等离子体基注渗的工艺方法，利用该方法可以根据工艺研究需要，实现注渗剂量、注渗能量(加速电压)和注渗温度单一参数调节，为等离子体体基注渗工艺的优化提供了一种切实可行的研究方法。利用本文提出的工艺方法，对纯铁进行了各种温度下的N离子注渗。结果表明，处理过程中，可依据工艺设计，单参数大范围改变注渗电压或注渗恒温温度，温度波动很小，离子注入层厚度得到明显提高。     

渗硼层脆性及其控制措施

分析了产生渗硼层脆性的本质属性和工艺因素两个方面的原因，提出了控制渗硼层脆性的4种途径：多元渗硼，改进渗硼工艺方法，控制渗层相的组成及其结构，渗硼层的再处理，其中以多元稀土共渗，超塑渗硼，激光渗硼和渗硼层的激光重熔技术等工艺方法控制脆性效果显著，同时，对几种实用的渗硼层脆性测试方法进行了对比和评述，为进一步发挥产品渗硼后的性能提供参考。     

无压浸渗工艺制备铝基复合材料的研究现状和机理探讨

无压浸渗法是一类先进的金属基复合材料制备方法.总结了无压浸渗方法制备陶瓷增强金属基复合材料的工艺特点及国内外的研究现状,分析了影响无压漫渗工艺的主要因素及存在的问题,探讨了该工艺的可能机理,并指出了该工艺存在的问题和今后的研究重点.     

H13钢自保护膏剂稀土渗硼工艺优化

目前鲜见针对H13钢铁稀土渗硼的工艺优化研究。为此,采用自保护膏剂对H13钢进行稀土渗硼试验,运用正交试验法考察了渗硼时间、渗硼温度、稀土含量对渗层厚度、显微组织、显微硬度的影响,从而优选渗硼工艺。结果表明:渗层厚度随着稀土含量的增大先增加后减少,渗硼温度和渗硼时间的增加均可提高渗层厚度。由此得到最优的稀土渗硼工艺参数为:渗硼温度950℃、渗硼时间4 h、稀土含量4%,在此最优工艺下稀土渗硼层厚度达92.1μm,比无稀土渗硼提高约70%;其中,稀土渗硼的高硬度层(大于800 HV)厚度达75μm,比无稀土渗硼提高约1倍,并且显微组织更为致密均匀,渗硼层与基体结合更为紧密。     

金属基复合材料的调压浸渗成形工艺

本文通过理论分析提出了一种新的金属基复合材料成形工艺——液相调压浸渗成形法,考察了可调工艺参数对浸渗过程的影响规律。实验表明,升压速度在很大程度上决定着材料的浸渗和凝固过程。采用调压浸渗成形工艺可以在较低的压力及模温下获得复合良好的金属基复合材料。     

液态法制备金属基复合材料浸渗动力学模型的研究进展

液态制备法因具有成本低、工艺简单和可操作性强等特点而广泛应用于金属基复合材料的工业化生产。其中,液态浸渗法制备复合材料的关键在于浸渗过程,因此如何控制浸渗过程中的工艺参数来制造高质量的复合材料是人们一直关注的课题。综述了液态法制备金属基复合材料的浸渗动力学模型研究现状,分析了当前研究中存在的问题,提出了相关建议,展望了复合材料浸渗动力学模型的发展趋势。     

渗铝管换热器的自动焊接

根据对渗铝管的管－板接工艺试验，分析了渗铝管的管－板接头的焊接性及影响焊接性的诸多因素。同时将渗铝管换热器的自动焊焊接工艺应用于生产中。     

Cr12MoV钢盐浴渗钒后的组织及耐蚀性能

目前,对Cr12Mo V盐浴渗钒层的耐蚀性鲜有研究。采用自配的混合盐对Cr12Mo V钢在不同温度和时间进行盐浴渗钒处理。通过表面显微硬度测试、金相显微和SEM形貌观察、EDS和XRD分析表征了Cr12Mo V渗层性能与组织结构,选定了较佳渗钒的温度(1 000℃)和时间(6 h),对最优工艺渗件在3.5%Na Cl溶液中进行了电化学测试,以检验渗层的耐蚀性。结果表明:Cr12Mo V钢渗钒后形成了致密的渗层,表面硬度从渗钒前的713HV3 N提高到1 800~2 700 HV3 N;渗层厚度分别与渗钒温度和保温时间成正比关系;最优工艺渗钒后的耐蚀性比渗钒前提高了36%。     

FABRICATION OF SiCp-AI COMPOSITE MATERIALS

Liquid phase fabrication methods for aluminum matrix composites reinforced with SiC whiskers, or SiC particles have been investigated and the mechanical properties of fabricated composites have been evaluated. Three kinds of liquid phase fabrication methods; hot extrusion, hot pressing and pressure infiltration, were studied. Commercial SiC whiskers and SiC powders of alpha type and beta type were used as the reinforcements for an aluminum matrix. Among the fabrication methods investigated, the best results were achieved by the pressure infiltration. The mechanical properties and the wear resistance of the fabricated composites were measured. The SiC whisker reinforced aluminum matrix composites have high strength, so that they can be used as high specific strength materials. The SiC particulate reinforced aluminum matrix composites are not strong as the SiC whisker reinforced composites. However, the SiC particulate reinforced aluminum matrix composites have a good potential for use as wear resistant material. The hardening effect of beta type particles on the aluminum matrix was larger than that of alpha type particles.     

晶须增强铝基复合材料润湿性行为的研究现状

提出液态浸渗法为晶须增强铝基复合材料的主要制备工艺,且基体与增强体的浸润程度是制造复合材料使其达到理想结构强度的关键,是反映界面性能的重要因素;介绍了在制备复合材料的过程中,润湿性的表征、实验方法及改善铝合金基体与增强体晶须润湿性的几种主要方式,并分析了这几种方式的优缺点;最后提出通过合适的工艺对晶须进行涂层处理,能够有效改善晶须与基体之间的润湿性,提高铝基复合材料的力学性能。     

碳化硅晶须增强铝复合材料的研究

本文工作集中于SiC_w/Al复合材料的制备、材料的微观结构分析和高温瞬时拉伸试验三方面。结果表明,用高压铸造法制造SiC_w/Al复合材料是可行的。用该方法制得的复合材料造价低廉,界面结合良好,具有优良的室温、高温强度和足夠的塑性。      

Processing of Al–SiCp Metal Matrix Composites by Pressureless Infiltration of SiCp Preforms

An optimum method for producing Al-SiC_p metal matrix composites was developed by determining the optimum conditions for wetting SiC by aluminum and the optimum parameters for pressureless infiltration of SiC_p preforms. The quantitative effect of magnesium and silicon additions to aluminum, free silicon on the SiC substrate, nitrogen gas in the atmosphere, and process temperature on the wetting characteristics of SiC by aluminum alloys was investigated using the sessile drop technique. The contribution of each of these parameters and their interactions, in terms of a relative power, to the contact angle, surface tension, and driving force for wetting were determined. In addition, an optimized process for enhanced wetting was suggested and validated. The optimum conditions for wetting SiC by aluminum that were arrived at were used to infiltrate SiC_p preforms and the mechanical properties of the resulting metal matrix composites were measured. The effect of SiC particle size, infiltration time, preform height, vol.% SiC in the preform, and Si coating on the SiC particles on the pressureless infiltration of SiC_p compacts with aluminum was investigated and quantified. The contribution of each of these parameters and their interactions to the retained porosity in the composite, the modulus of elasticity, and the modulus of rupture were determined. Under optimum infiltration conditions, metal matrix composites with less than 3% porosity, over 200 GPa modulus of elasticity, and about 300 MPa modulus of rupture were routinely produced.     

Effect of the Aluminum Matrix on Tensile Properties of Carbon Fiber/Al Composites Prepared by Liquid Extrusion Infiltration

Strength of Materials - Two-dimensional T300 carbon fiber-reinforced aluminum alloy matrix (2D CF/Al) composites were prepared by the liquid extrusion infiltration (LEI) process with the matrices...     

SiCp/Al Composites Fabricated by Modified Squeeze Casting Technique

A cost effective method was introduced to fabricate pure aluminum matrix composites reinforced with 20% volume fraction of 3.5 μm SiC particles by squeeze casting followed by hot extrusion. In order to lower volume fraction of the composites, a mixed preform containing pure aluminum powder and the SiC particles was used. The suitable processing parameters for the infiltration of pure aluminum melt into the mixed preform are： melt temperature 800℃, preform temperature 500℃, infiltration pressure 5 MPa, and solidification pressure 50 MPa. Microstructure and properties of the composites in both as-cast and hot extruded states were investigated. The results indicate that hot extrusion can obviously improve the mechanical properties of the composite.     

颗粒增强Al/Si复合材料的制备工艺研究

研究用浸渗法制备颗粒增强铝硅复合材料的工艺。采用加压渗流将铝液压入到硅颗粒间隙中制备复合材料,分析了不同粒度颗粒增强相对复合材料浸渗长度及Si含量的影响。结果表明：利用浸渗法制得的Al—Si复合材料硅的体积分数可高达60％以上,随颗粒度的减小而增加。     

颗粒增强铝基复合材料废料回收的试验研究

为了回收铝合金基体材料,配制了合适的混合盐熔剂,采用熔融盐法去除颗粒增强铝基复合材料中的增强材料。进行了金相观察和X射线衍射分析,并测定基体合金的回收率,结果表明复合材料中的增强材料能被一定量的熔融盐去除,其回收利用率大约为85%。      

碳化硅颗粒增强Al基复合材料的新型制备工艺

综述了碳化硅增强铝基复合材料的几种主要制备工艺,重点阐述了高能超声半固态复合法制备SiCp/Al复合材料.首先用渗流法制备SiC体积分数高的SiCp/Al预制块,进行SiC预分散,然后将预制块加入处于半固态温度条件下的铝合金熔体中,最后导入超声波进行搅拌.此法很好地改善了增强颗粒与基体之间的润湿性,使SiC在基体中均匀...     

粉煤灰颗粒增强铝基复合材料的研究与进展

粉煤灰颗粒增强铝基复合材料因低廉的价格与优异的性能日益受到人们关注.介绍了粉煤灰颗粒增强铝基复合材料常用的制备方法(搅拌铸造法、压力浸渗法以及粉末冶金法);指出了各种制备工艺的优缺点;阐述了粉煤灰颗粒增强铝基复合材料优良的性能,特别是其力学性能、耐磨性能、阻尼性能与电磁屏蔽性能;展望了粉煤灰颗粒增强铝基复合材料的发展趋势.