(1. 中南大學(xué) 粉末冶金國家重點(diǎn)實(shí)驗(yàn)室，長沙 410083；2. 湘潭大學(xué) 機(jī)械工程學(xué)院，湘潭 411105；3. 株洲硬質(zhì)合金集團(tuán)有限公司，株洲 412000)
摘 要: 對缺碳硬質(zhì)合金采用滲碳處理制備梯度硬質(zhì)合金，利用顯微組織分析和維氏硬度測試等方法，研究滲碳工藝對梯度硬質(zhì)合金的梯度結(jié)構(gòu)和硬度的影響。結(jié)果表明：滲碳處理后隨著滲碳時(shí)間延長，梯度層厚度增大，長時(shí)間滲碳還會(huì)出現(xiàn)梯度結(jié)構(gòu)消失現(xiàn)象；滲碳時(shí)表面層WC晶粒長大，且滲碳時(shí)間越長晶粒長大越嚴(yán)重；滲碳后梯度硬質(zhì)合金的表面硬度明顯提高；滲碳后合金的表面硬度明顯高于燒結(jié)態(tài)合金的表面硬度；隨著滲碳時(shí)間的延長，合金表面硬度先增大后減小；合金的硬度在截面上沿梯度方向呈連續(xù)梯度變化，合金表面層因WC含量較高、鈷含量較低而具有較高的硬度，中間層因鈷含量較高、WC含量較低，其硬度較低。
關(guān)鍵字: WC-Co硬質(zhì)合金；梯度結(jié)構(gòu)；滲碳；硬度
（1. State Key Laboratory of Powder Metallurgy , Central South University , Changsha 410083, China;2. School of Mechanical Engineering, Xiangtan University, Xiangtan 411105, China;3. Zhuzhou Cemented Carbide Group Ltd., Zhuzhou 412000, China）
Abstract: Gradient cemented carbides were prepared by carburizing carbon-deficient cemented carbides. The effects of carburizing processes on the gradient structure and hardness of WC-Co gradient cemented carbides were investigated by optical microscopy, scanning electron microscopy and Vickers hardness test. The results show that the thickness of gradient structure increases with prolonging of carburizing time and the gradient structure disappears after long time carburizing. WC grains in the surface layer grow after carburizing and the growth degree increases with carburizing time. The surface hardness of as-carburized alloys is obviously higher than that of as sintered alloys, which increases firstly then decreases with prolonging carburizing time. The hardness of as-carburized alloys in the cross section varies continuously and gradiently along gradient direction, namely the hardness is higher in the surface layer for higher WC content and lower cobalt content, which is lower in the middle layer for higher cobalt content and lower WC content.
Key words: WC-Co cemented carbides; gradient structure; carburizing; hardness
