【摘要】：化學氣相沉積(Chemical Vapor Deposition,CVD)金剛石具有許多和天然金剛石類似的優(yōu)異性能,如涂層具有高硬度、低摩擦系數(shù)、低熱膨脹系數(shù)、高耐磨性以及很好的化學穩(wěn)定性等優(yōu)良性能,是良好的耐磨減摩涂層材料,其耐磨性能是硬質(zhì)合金的50~200倍。高速鋼材料工具具有較高的韌性,在我國刀具與耐磨器件領(lǐng)域應(yīng)用廣泛,然而其耐磨性較差容易磨損,造成資源的巨大浪費。因此,在高速鋼襯底表面沉積CVD金剛石涂層可以將金剛石涂層的優(yōu)異性能與襯底的韌性完美的結(jié)合在一起,提高高速鋼工具的使用性能,發(fā)展前景廣闊。然而在高速鋼襯底表面很難直接出沉積高質(zhì)量的CVD金剛石涂層,本文針對高速鋼襯底表面直接沉積高質(zhì)量CVD金剛石涂層的關(guān)鍵技術(shù)難點進行了深入研究,主要完成的研究內(nèi)容如下:1、W18Cr4V高速鋼襯底表面CVD金剛石涂層的預(yù)處理新方法研究。本文提出一種梯度應(yīng)力分布的Ni-P/Cu復(fù)合中間過渡層技術(shù),Ni-P/Cu復(fù)合中間過渡層隔使催石墨化的襯底材料元素滲透到其表面,從而提高金剛石的形核率,同時阻止反應(yīng)氣源產(chǎn)生的碳向襯底表面滲透,有效保護襯底。此外,Cu層較軟可以有效吸收金剛石涂層在生長冷卻過程產(chǎn)生的殘余應(yīng)力降低涂層的內(nèi)應(yīng)力。2、開展了CVD金剛石涂層的低溫沉積技術(shù)研究。采用HFCVD法制備金剛石涂層,通過提高氣流的流量以降低沉積溫度,合理控制反應(yīng)腔內(nèi)的溫度以減小涂層的熱應(yīng)力。沉積工藝參數(shù)對金剛石具有重要影響,試驗分別研究了沉積壓力、碳氫氣體流量比、溫度、以及預(yù)處理方式對CVD金剛石涂層的影響。通過掃描電鏡、XRD、拉曼光譜、洛氏硬度計對沉積的涂層的成分結(jié)構(gòu)、表面形貌以及附著強度等性能進行檢測分析。在沉積壓力為4 k Pa、溫度450℃、碳氫氣體的流量比為30/300、偏流1.5 A、熱絲與襯底表面間距9~10 mm時,在化學鍍2.5 h、電鍍銅10 min的Ni-P/Cu復(fù)合過渡層表面沉積的金剛石涂層純度高,附著強度好。此外,化學鍍2.5 h的單層過渡層沉積的金剛石涂層也具有較高的表面形貌。3、研究了中間過渡層、摩擦配副材料對W18Cr4V高速鋼襯底CVD金剛石涂層摩擦性能的影響。本文初步研究了軸承鋼、銅配副材料對不同過渡層表面的CVD金剛石涂層的摩擦磨損性能的影響。銅配副材料的摩擦系數(shù)比軸承鋼的要大,而且銅對摩副表面不僅存在磨粒磨損,同時存在嚴重的粘著磨損,而軸承鋼對摩副表面磨粒磨損較為明顯而沒有明顯的粘著磨損;當對摩副材料相同時,Ni-P單層過渡層試樣的摩擦系數(shù)較Ni-P/Cu復(fù)合過渡層的要小,原因是其表面金剛石顆粒大小均勻且表面粗糙度較低,但是由于金剛石涂層與Ni-P層的附著強度較低,涂層會在較短時間內(nèi)磨損剝落。
[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，

本文編號：2409892