W18Cr4V高速钢衬底金刚石涂层制备及其摩擦磨损试验研究

发布时间：2019-01-17 09:24

【摘要】：化学气相沉积(Chemical Vapor Deposition,CVD)金刚石具有许多和天然金刚石类似的优异性能,如涂层具有高硬度、低摩擦系数、低热膨胀系数、高耐磨性以及很好的化学稳定性等优良性能,是良好的耐磨减摩涂层材料,其耐磨性能是硬质合金的50~200倍。高速钢材料工具具有较高的韧性,在我国刀具与耐磨器件领域应用广泛,然而其耐磨性较差容易磨损,造成资源的巨大浪费。因此,在高速钢衬底表面沉积CVD金刚石涂层可以将金刚石涂层的优异性能与衬底的韧性完美的结合在一起,提高高速钢工具的使用性能,发展前景广阔。然而在高速钢衬底表面很难直接出沉积高质量的CVD金刚石涂层,本文针对高速钢衬底表面直接沉积高质量CVD金刚石涂层的关键技术难点进行了深入研究,主要完成的研究内容如下:1、W18Cr4V高速钢衬底表面CVD金刚石涂层的预处理新方法研究。本文提出一种梯度应力分布的Ni-P/Cu复合中间过渡层技术,Ni-P/Cu复合中间过渡层隔使催石墨化的衬底材料元素渗透到其表面,从而提高金刚石的形核率,同时阻止反应气源产生的碳向衬底表面渗透,有效保护衬底。此外,Cu层较软可以有效吸收金刚石涂层在生长冷却过程产生的残余应力降低涂层的内应力。2、开展了CVD金刚石涂层的低温沉积技术研究。采用HFCVD法制备金刚石涂层,通过提高气流的流量以降低沉积温度,合理控制反应腔内的温度以减小涂层的热应力。沉积工艺参数对金刚石具有重要影响,试验分别研究了沉积压力、碳氢气体流量比、温度、以及预处理方式对CVD金刚石涂层的影响。通过扫描电镜、XRD、拉曼光谱、洛氏硬度计对沉积的涂层的成分结构、表面形貌以及附着强度等性能进行检测分析。在沉积压力为4 k Pa、温度450℃、碳氢气体的流量比为30/300、偏流1.5 A、热丝与衬底表面间距9~10 mm时,在化学镀2.5 h、电镀铜10 min的Ni-P/Cu复合过渡层表面沉积的金刚石涂层纯度高,附着强度好。此外,化学镀2.5 h的单层过渡层沉积的金刚石涂层也具有较高的表面形貌。3、研究了中间过渡层、摩擦配副材料对W18Cr4V高速钢衬底CVD金刚石涂层摩擦性能的影响。本文初步研究了轴承钢、铜配副材料对不同过渡层表面的CVD金刚石涂层的摩擦磨损性能的影响。铜配副材料的摩擦系数比轴承钢的要大,而且铜对摩副表面不仅存在磨粒磨损,同时存在严重的粘着磨损,而轴承钢对摩副表面磨粒磨损较为明显而没有明显的粘着磨损;当对摩副材料相同时,Ni-P单层过渡层试样的摩擦系数较Ni-P/Cu复合过渡层的要小,原因是其表面金刚石颗粒大小均匀且表面粗糙度较低,但是由于金刚石涂层与Ni-P层的附着强度较低,涂层会在较短时间内磨损剥落。
[Abstract]:Chemical vapor deposition (Chemical Vapor Deposition,CVD) diamond has many excellent properties similar to natural diamond, such as high hardness, low friction coefficient, low thermal expansion coefficient, high wear resistance and good chemical stability. It is a good antifriction coating material and its wear resistance is 200 times of that of cemented carbide. High speed steel tools have high toughness and are widely used in the field of cutting tools and wear-resistant devices in China. However, their poor wear resistance is easy to wear, resulting in a huge waste of resources. Therefore, CVD diamond coating deposited on the substrate of high speed steel can combine the excellent properties of diamond coating with the toughness of substrate perfectly, improve the performance of high speed steel tools, and have a bright future. However, it is difficult to deposit high quality CVD diamond coating directly on the surface of high speed steel. In this paper, the key technical difficulties of direct deposition of high quality CVD diamond coatings on high speed steel substrates are studied. The main contents are as follows: 1. The new pretreatment method of CVD diamond coating on W18Cr4V high speed steel substrate. In this paper, a gradient stress distribution (Ni-P/Cu) composite intermediate layer technique is proposed. The intercalation of Ni-P/Cu composite intermediate layer permeates the surface of graphitized substrate material elements, thus increasing the nucleation rate of diamond. At the same time, the carbon produced by the reactive gas source is prevented from infiltrating into the substrate surface, which effectively protects the substrate. In addition, the soft Cu layer can effectively absorb the residual stress produced by the diamond coating during the growth and cooling process to reduce the internal stress of the coating. 2. The low temperature deposition technology of the CVD diamond coating has been studied. Diamond coating was prepared by HFCVD method. The thermal stress of the coating was reduced by increasing the flow rate of gas in order to reduce the deposition temperature and to control the temperature in the reaction chamber reasonably. The effects of deposition pressure, flow ratio of hydrocarbon gas, temperature and pretreatment method on CVD diamond coating were studied. The composition, surface morphology and adhesion strength of the deposited coatings were investigated by scanning electron microscopy, XRD, Raman spectroscopy and Rockwell hardness tester. When the deposition pressure is 4k Pa, temperature 450 鈩，

本文编号：2409892