铬含量对高碳铬铁铸渗层组织及性能的影响

采用铸渗工艺在45钢表面获得高碳铬铁铸渗层,通过改变铸渗合金粉末中Cr含量,研究了Cr含量对铸渗层组织及性能的影响。结果表明:铸渗层与基体呈良好的冶金结合,主要的碳化物有Cr_7C_3、Fe_3C、Cr_(23)C_7;并且随着Cr含量的增加,菊花状弥散分布的Cr_7C_3型碳化物明显增多,当合金粉末中铬含量为60%时,铸渗层硬度较高,此时铸渗层耐磨性能最佳,是基体的1.7倍。     

铸渗法获得表面粒子增强复合材料的研究

在试验基础上,研究了铸渗法制造表面粒子增强复合材料,可以在HT200基体上获得均匀、致密的铸渗层,厚度为3mm左右。对铸渗工艺进行了优化,同时研究了合金层的铸态组织和主要合金成分在铸渗层中的分布规律。     

铸渗法制备三元硼化物硬质覆层-钢基体界面特性的分析

采用反应铸渗法在钢基体表面制备一层三元硼化物硬质覆层材料,研究了铸渗三元硼化物覆层与钢基体界面区的显微硬度,用SEM-EDS研究了界面的显微组织结构和元素分布,对铸渗反应机理进行了初步讨论。研究结果表明,通过反应铸渗法制备的三元硼化物硬质覆层-钢基体界面处存在一个由覆层高硬度到钢基体低硬度的狭窄的过渡区。显微组织观察与成分分析表明,覆层与钢基体在界面结合处实现了合金元素的扩散与渗透,并且两者形成了良好的冶金结合。     

添加Mn对高碳铬铁铸渗复合材料组织的影响

利用铸渗工艺在ZG45钢表面获得高锰高碳的铬铁铸渗层,通过改变铸渗合金粉中锰含量,研究了锰对铸渗表面复合材料组织均匀性及性能的影响。结果表明:获得的铸渗层厚度在6 mm以上;当自制合金粉末中锰含量为11%时,获得的铸态组织中碳化物以菊花状弥散均匀地分布在奥氏体基体中,碳化物主要有Cr7C3、Fe3C、Cr23C6等,铸渗层致密,无气孔,铸渗层与基体之间为冶金结合,且此时硬度达到最大值HRC56。     

铸渗法制备三元硼化物硬质覆层一钢基体界面特性的分析

采用反应铸渗法存钢基体表面制备一层三元硼化物硬质覆层材料,研究了铸渗三元硼化物覆层与钢基体界面区的显微硬度,用SEM-EDS研究了界面的显微组织结构和元素分布,对铸渗反应机理进行了初步讨论.研究结果表明,通过反应铸渗法制备的三元硼化物硬质覆层.钢基体界面处存在一个南覆层高硬度到钢基体低硬度的狭窄的过渡区.显微组织观察与成分分析表明,覆层与钢基体存界面结合处实现了合金元素的扩散与渗透,并且两者形成了良好的冶金结合.     

球墨铸铁表面钨铬铸渗层研究

研究了铸渗法制造表面粒子增强复合材料,可以在ＱＴ６００－３基体上获得均匀、致密的铸渗层,厚度为３ｍｍ以上。同时,研究了球墨铸铁铸渗层的铸态组织,硬度和合金成分在铸渗层中的分布规律,并现场试验了粉碎机摆锤耐磨粒磨损性能。     

纳米陶瓷中间合金增强高铬铸铁铸渗层的研究

采用将纳米陶瓷颗粒单独加入或者混入中间变质合金后加入两种方法,通过传统的砂型铸渗工艺在中碳铸钢ZG270-500表面分别制备出纳米粉末增强高铬铸铁铸渗层和纳米变质合金增强高铬铸铁铸渗层两种材料。通过微观组织分析和耐磨性能测试发现:将纳米TiN颗粒以粉末形式直接加入,渗层中的碳化物分散较为均匀,但仍保留有不明显的网状特征;加入变质合金的渗层中碳化物呈颗粒状、棒状或层片状独立分布;若变质合金中加入稀土,渗层中碳化物呈细小的颗粒状,在基体中均匀弥散分布,因此它的硬度较高,耐磨性能最好。     

铸钢表面铸渗WC颗粒材料界面与磨损性能的研究

研究了一种以中碳低合金钢作为基体材料,借鉴颗粒增强钢基表面复合材料铸渗技术,结合消失模铸造技术,并在其表面进行颗粒增强相铸渗的材料。通过研究颗粒预制体骨架材料与成型工艺,制备高耐磨颗粒增强铸渗锤头,其特征为具有一定厚度及颗粒分散度的铸渗层。试验样块铸渗增强相颗粒层达到7~10 mm;热处理后,颗粒增强层表面基体平均硬度为581.3 HV,颗粒平均硬度为1 890.6 HV。磨损试验结果表明,3种材料耐磨性大小依次为铸渗颗粒层高铬铸铁试验钢(不含颗粒),且铸渗颗粒增强层的静摩擦磨损性能理论上为试验高铬铸铁的7~8倍。     

成分对铁基表面铸渗SiC颗粒影响研究

对不同铁基材料进行表面SiC颗粒复合研究。通过对比不同基体中铸渗复合试样的金相组织特征及复合层硬度变化,探讨了优化铁基表面SiC颗粒复合材料制备工艺的方向。结果表明,在钢铁基体上采用铸渗工艺复合SiC颗粒过程中,存在SiC颗粒的分解及C、Si原子扩散过程。基体中高的铬含量使铸渗层生成大量碳化物,抑制了石墨相的生成,并使得铸渗层硬度比基体增长近1倍。基体中高的Si、C含量能抑制SiC颗粒的分解,获得残留SiC颗粒的铸渗层,但是颗粒尺寸大幅度减小且形状由不规则四边形变为近似圆形。     

用铸渗法改善球铁铸件表面耐磨性的研究

本文采用铸渗钒、钛合金来改善球铁铸件(粉碎机锤头)表面的耐磨性,研究结果表明,球铁经铸渗钒钛合金后,在表面形成一层厚度为0.3～0.35mm的白口层基体,其上分布着合金碳化物,经工业性实验证明,用钒钛合金铸渗的球铁件的使用寿命是未用钒钛合金铸渗的球铁件的使用寿命的131～144％。     

Effect of rapid solidification on the microstructure and corrosion behaviour of Al-Zn-Mg based material

The corrosion behaviour of Al-5Zn-3Mg-0.6Cu-0.8Zr-0.25Cr-0.15Ni-0.15Ti alloys, produced by traditional and powder technologies, with similar thermo-mechanical treatments, in 3% sodium chloride solution, has been examined by electrochemical methods, scanning electron microscopy, transmission electron microscopy and X-ray microanalysis. The alloys reveal similar precipitation but of different shape, size and distribution; further, both alloys experience localized corrosion. Copper-rich precipitates initiate the dissolution of surrounding particles, enriched in Zn and Mg. As a result, the surface is enriched with other alloying elements after a full polarisation run. Cast material has lower corrosion properties because of the higher heterogeneity of the structure. The structure heterogeneity of the cast material involves a more non-uniform distribution of the precipitates, larger Zn- and Mg-rich particles, and depletion of the matrix and areas around the precipitates by alloying elements compared with the powder material.     

铸渗合金层的温度场测试与分析

通过对合金粉膏块内外界面上温度变化曲线的测试,计算出了膏块在合金化形成过程中的热扩散率。并对铸渗合钓饵支外表面上的温度曲线做了分析。     

Mg alloy surface alloying layer fabricated through evaporative pattern casting technology

The influencing factors of surface alloying layer by evaporative pattern casting technology were investigated.A certain thickness alloying layer was formed on the surface of Mg-alloy matrix when the pouring temperature was 780°C with different vacuum degree and alloying powder size.The surface layer microstructure,micro area composition of the new phase formed on the matrix and the composition characteristics on the surface layer were examined by SEM and element scanning.The results show that the content of aluminum increases greatly on the surface layer.The micro-hardness of alloyed layer has a more obvious increase compared with that of the matrix.The size of alloying element and the vacuum degree are the key factors influencing the alloying layer,with the increase of element powder size from 0.074 to 0.15 mm and vacuum degree from 0.04 to 0.06 MPa,the surface alloying effect becomes better.     

Interaction between alloying and hardening of cast iron surface

To improve wear resistance of surface will increase the service life of gray cast iron directly.This paper presents that gray cast iron surface coated with alloy powder is locally remelted by TIG arc of increase the wear resistance.The influences of arc current and scanning rate etc on surface properties are found.Under different conditions.the microstructure,hardness and wear resistance of remelted layer are analyzed and measured.The results indicate that the gray cast iron surface can be strengthened by TIG arc local remelting treathent.Especially,surface alloying hardening effect is best and surface properties are improved remarkably.     

消失模法高锰钢表面合金化工艺的研究

利用干砂负压消失模铸造工艺对高锰钢表面合金化进行研究,通过正交试验研究合金粉配比、助熔剂和粘结剂含量、合金涂层厚度等因素对表面合金层质量的影响,确定合金化涂料的最佳配比,分析表面合金层的组织和性能。结果表明：表面合金层由表及里分为烧结区、过渡区和熔合区,其外层为耐磨性能较好的烧结区和过渡区,内层为综合性能较好的熔合区,基体为奥氏体组织。     

微合金化灰铸铁气焊丝焊接接头组织与性能

以弱碳化焰熔化微合金化灰铸铁焊丝,并充填灰铸铁棒材U型坡口,通过金相观察接头微观组织,发现铸铁同质焊缝微观组织对微合金化元素含量十分敏感,微合金化处理能够实现焊缝金属与基体金属的高强度冶金结合,微合金元素促进焊缝石墨化,并有效避免白口组织及焊接裂纹形成.焊接接头抗拉强度高于基体且硬度接近基体金属,机械加工性能良好.微合金化气焊丝成分可调,可满足各种牌号灰铸铁件的气焊需要.     

Microstructure Development during Extrusion of Mechanically Alloyed Powder

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钴粉包覆的铸造WC颗粒在金刚石锯片中的应用

对铸造WC、Co粉包覆铸造WC和Ni粉包覆铸造WC颗粒3种材料在金刚石锯片中的应用进行研究,探究其对金刚石锯片胎体机械性能、微观形貌及锯片切割性能的影响。结果表明:当3种材料与金属粉末的质量比都为3∶1时,形成的3种胎体的硬度相当。含Co粉包覆铸造WC的胎体抗弯强度最高,WC颗粒与胎体界面的结合最紧密,胎体显微组织最致密;含Ni粉包覆铸造WC的胎体的抗弯强度次之;仅加入铸造WC的胎体的抗弯强度最差。与仅加入铸造WC的锯片相比,Co粉包覆铸造WC应用到锯片中,其锯片的切割寿命最长,提高了40%。      

Sintering of a nano-crystalline tungsten heavy alloy powder

A nano-crystalline Tungsten heavy alloy powder was obtained by mechanical alloying of elemental powders in a jar mill with a high ball to powder ratio. The chemical composition of the primary powder was 93 W-4.9Ni-2.1Fe (wt%). The mechanically alloyed powder had 22 nm sized tungsten crystallites distributed in an amorphous nickel base phase. Mechanical alloying reduced particle size of powders and also yielded to more uniform particles size distribution. Sintering behavior and microstructural development of that powder were studied and compared with a conventionally mixed powder. Mechanically stored energy and better distribution of primary elements in Nano-crystalline powder had decreased motivation energy of sintering and that powders showed more densification at relatively lower sintering temperatures. Sintering at low temperatures can depress grain growth during sintering and provide desirable properties. A transient intermetallic phase was formed in the nano-crystalline powder during sintering that has not been seen in conventionally mixed powders.     

表面喷焊处理对铸铁表面组织和性能的影响

利用镍基自熔合金粉末,采用氧乙炔火焰喷焊技术在灰铸铁HT200基体表面制备喷焊层,研究了喷焊层的成分分布、组织与性能。结果表明,镍基喷焊层与铸铁基体形成了良好的冶金结合,合金元素在喷焊层与基体界面附近连续分布,保证了采用火焰喷焊技术得到的涂层与基体之间具有较高的结合强度。