原位合成及外加法制备碳化钒颗粒增强铁基复合材料的研究

通过粉末冶金工艺制备碳化钒颗粒增强铁基复合材料，研究了原住合成和外加法对复合材料烧结密度、性能及组织结构的影响，并借助金相、SEM、EDS观察了碳化钒的分布及元素成分。试验结果表明：原位合成复合材料具有更高的烧结密度和抗弯强度，在1280℃时达到最大值，分别为7．4g．cm^-3和983MPa，在烧结过程中反应生成了碳化钒颗粒，主要分布在晶界；外加法中的碳化钒颗粒分布更均匀，并通过扩散作用融入Cr、Mo、Fe等合金元素。

铸造烧结VC-Fe基表面复合材料

利用铸造烧结新技术 ,在铸件表面原位生成 1层厚为 3～ 4mm由大量VC颗粒和Cr的碳化物组成的复合材料 ;通过对复合材料层组织结构的研究和热力学分析 ,对铸造烧结机理作了初步研究 ;指出铸造烧结与铸渗原理是不同的。

原位合成VC颗粒增强钢基复合材料组织及其形成机理

研究了铸造法制备的原位 VCP增强钢基复合材料的组织和性能 ,探讨了复合材料的组织形成机理。结果表明 ,原位 VCP增强钢基复合材料具有浇铸温度低 (172 3～ 1773K) ,铸造成型性好的特点 ,适用于制备体积分数较高的颗粒内生复合材料 ;原位合成的 VC颗粒细小 ,体积分数可达 15 %左右 ,并在基体中均匀分布 ;在复合材料组织中发现三种类型的 VC增强相 ,即自熔体中析出的颗粒状 VC,条状共晶 VC和二次析出粒状 VC;通过基体合金化 ,可以明显提高复合材料的组织稳定性 ,经 92 3K回火后 ,硬度可维持在 HRC6 0左右 。

铸造烧结VC-Fe基表面复合材料耐磨性研究

利用对比试验 ,运用扫描电子显微镜、能谱仪和XRD等手段对VC Fe基表面复合材料的耐磨性做了初步的分析研究。结果表明 ,V含量、VC颗粒形状及分布对表面复合材料耐磨性有明显的影响 ,含V量越高 ,VC颗粒越规则 。

液相合成VC颗粒增强钢基表面复合材料研究

利用液相合成技术，通过铸造在钢件上形成一层３—４ｍｍ厚，以ＶＣ颗粒增强的表面复合材料。组织结构和微区成分分析表明，在该表面复合材料的马氏体基体上均匀分布细小球状ＶＣ颗粒和条块状（Ｆｅ，Ｃｒ）７Ｃ３，由表及里，其合金元素浓度及ＶＣ的数量均呈梯度分布。在重载干滑动磨损条件下，含有自润滑石墨相的该表面复合材料具有很好的耐磨性。

Warm compacted NbC particulate reinforced iron-base composite(Ⅰ)--Effect of fabrication parameters

NbC was used as reinforced particles in the fabrication of iron base composite. Ball milling was introduced to overcome the problems of agglomeration and powder separation during powder mixing. After ball milling, the fine NbC particles are embedded on the surface of iron particles and evenly distributed in the mixed powders. Warm compaction was used not only to increase the green density but also to improve the formability of the mixed powder and to improve the compact’s green strength to facilitate handling. The influences of fabrication parameters such as ball milling time, annealing temperature and time, warm compaction temperature, sintering temperature and sintering time were studied. Compacts with a relative sintered density of 97% and a tensile strength of more than 800?MPa can be obtained by using a ball milling time of 5?h, an annealing temperature of 800?℃, a compaction pressure of 600?MPa, warm compaction temperature of 120?℃, sintering temperature of 1?280?℃, and sintering time of 80?min. The shrinkage at this sintering condition was approximately 4.3%.

Warm compacted NbC particulate reinforced iron-base composite(Ⅱ)--Microstructure and properties

Effects of different sintering temperature and sintering time on the relative density of the sintered compacts were studied to obtain the optimal sintering parameters for the fabrication of NbC parti culate reinforced iron base composite. With optimal sintering temperature of 1?280?℃ and sintering time of 80?min, wear resisting, high density NbC particulate reinforced iron base composites can be obtained using warm compaction powder metallurgy. The microstructure, relative density, mechanical properties and tribological behaviors of the sintered composites were studied. The results indicate that the mechanical properties of the sintered compacts were closely related to the sintered density. The iron base composite materials with different combinations of mechanical properties and tribological behaviors were developed for different applications. One of the developed composite, which contains 10%NbC, possesses a high strength of 815?MPa with a remarkable friction and wear behaviors. The other developed composite, which contains 15%NbC, possesses a lesser strength of 515?MPa but with excellent friction and wear behaviors.

激光熔覆原位生成VC增强Fe-Ni基复合涂层的组织与硬度

针对高速电梯制动瓦块材料耐高温磨损性差的问题,以V粉和Ni基合金粉末为原料,进行了激光熔覆原位生成VC增强Fe-Ni基复合涂层的试验,分析了不同粉末质量配比、不同工艺参数下熔覆层的组织演变规律和硬度性能。研究表明:通过原位反应可获得主要由VC、Cr3C2、Fe3C和Ni-Fe固溶体组成的陶瓷复合涂层;VC的含量随V含量的增加而增加;在较低的扫描速度下,VC颗粒呈梅花状或菊花状弥散分布。当扫描速度较高时,VC呈胞状和块状,主要分布在晶界上;V含量10%、30%、50%对应的熔覆层平均硬度分别为562、715、908 HV0.2。