机械合金化制备非化学计量比碳化钨及其烧结性能研究

发布时间：2018-07-28 11:00

【摘要】：本文主要研究了利用机械合金化方法制备过渡族金属碳化物纳米晶粉体碳化钨，并利用X射线衍射方法理论对不同球磨时间的粉体进行了定性分析和定量分析，研究其物相组成、晶粒大小、各相成分含量，并对机械合金化的过程进行了分析。另一方面，应用放电等离子烧结的方法对碳化钨纳米晶粉体进行了烧结致密化，并对得到的烧结体进行了X射线衍射分析，分析其物相组成，晶粒大小，各相成分含量，并对比了烧结前后的样品的各种变化。除此之外，本文研究了烧结过程中样品的位移以及位移率伴随烧结温度所表现的变化特点，对放电等离子烧结过程进行了理论分析。最后，对烧结体进行了一系列的性能测试。 XRD分析结果表明，在高能球磨的作用下，样品发生了机械激活和化学激活，成功合成了新的物质W2C和WC。随着球磨时间的增加，W单质的含量逐渐减少，W2C的含量先增加后减少，WC的含量逐渐增加，球磨70h的样品中WC的含量占到了100%，，说明在球磨过程中W2C仅是生成WC的中间产物。在球磨过程中原始粉的颗粒尺寸减小，晶粒细化，说明机械合金化确实可以细化晶粒。烧结实验结果表明，我们成功地制备了WC块体；通过对其X射线衍射图进行全谱拟合分析，结果表明球磨时间越长，样品的碳含量越高，因此通过控制球磨时间可以调控碳含量。此外，我们发现球磨时间越长，烧结样品的密度越小，球磨40h的烧结体的硬度最大，可达到2250HV。所以可以看出机械合金化和放电等离子烧结方法的搭配在一定的条件下可以产生性能优异的过渡族金属碳化物纳米晶烧结体碳化钨。
[Abstract]:In this paper, the preparation of transition metal carbide nanocrystalline tungsten carbide by mechanical alloying method was studied. The qualitative analysis and quantitative analysis of the powders with different milling time were carried out by using the theory of X-ray diffraction. The phase composition, grain size and composition content of each phase were studied, and the process of mechanical alloying was analyzed. On the other hand, the sintering densification of tungsten carbide nanocrystalline powder was carried out by spark plasma sintering, and the phase composition, grain size and content of each phase were analyzed by X-ray diffraction. The changes of samples before and after sintering were compared. In addition, the variation characteristics of the displacement and displacement rate of the sample with sintering temperature during sintering were studied, and the SPS process was analyzed theoretically. Finally, a series of performance tests were carried out on the sintered body. The results of XRD analysis showed that the samples were mechanically and chemically activated under the action of high energy ball milling, and the new substances W2C and WC were successfully synthesized. With the increase of milling time, the content of W _ 2C increased firstly and then increased gradually, and the content of WC in the sample of 70 h ball milling accounted for 100%, indicating that W2C was only the intermediate product of WC formation during ball milling. In the process of ball milling, the particle size of the original powder decreases and the grain is refined, which indicates that mechanical alloying can refine the grain. The results of sintering experiment show that the WC block has been successfully prepared and the carbon content of the sample increases with the increase of ball milling time through the full-spectrum fitting analysis of its X-ray diffraction pattern. Therefore, the carbon content can be controlled by controlling the milling time. In addition, we found that the longer the ball milling time, the smaller the density of the sintered sample, and the maximum hardness of the sintered material was 2250 HV after 40 h ball milling. Therefore, it can be seen that the combination of mechanical alloying and spark plasma sintering can produce transition metal carbide nanocrystalline tungsten carbide with excellent properties under certain conditions.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TF123.31;TF124.5

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