溶胶-凝胶法制作陶瓷涂层硬质合金刀具

CERAMIC-COATED CEMENTED CARBIDE CUTTING TOOLS BY SOL-GEL ROUTE

以异丙醇铝为前驱物 ,将溶胶 -凝胶工艺应用于硬质合金刀片涂层 ,研制成功一种新型的陶瓷涂层刀片。使用浸渍提拉法对刀具基体进行涂层 ,在基体表面获得勃姆石凝胶膜 ,经 1 2 0 0℃热处理后可以得到厚度适宜的α -Al2 O3涂层 ,涂层完整 ,无宏观缺陷 ,并且在初步的切削实验中显示出一定效果 ,从而为涂层刀具制造展示了一种全新的涂层方法。利用扫描电子显微镜 (SEM)观察了涂层的表面形貌 ,用X射线衍射 (XRD)和电子探针 (EPMA)分析了涂层的表面和界面的成分和微观结构。实验结果表明 ,涂层在 1 1 4 0℃左右转化成α -Al2 O3,在 1 2 0 0℃烧结致密 ,而在 1 2 50℃以上涂层发生明显收缩 ,晶粒明显长大 ;最终的涂层为多晶体结构 ,涂层界面未生成弱化相 ;硬质合金中的部分钴元素扩散到涂层中 ,有助于提高涂层和基体间的粘结强度。

Ceramic_coated cemented carbide cutting tools were prepared from aluminum alkoxide solution and carbide substrates by sol-gel route. The carbide substrates is coated with boehmite sol by dip_coating process and dried to get gel film. After the heat treatment at 1 200 ℃, the coating with a thickness up to more than 6 μm can be obtained without any macroscopic defect and shows good performance in cutting medium carbon steel, which presents a novel and promising coating method for cutting tools. The coating morphology was examined with the aid of scanning electron microscope(SEM). The composition of the coating and interface layer was characterized by X -ray diffraction(XRD). The results suggest that the coating converts to α -alumina at about 1 140 ℃ and sinters to relatively high density at 1 200 ℃. The coating is polycrystalline and isotropic and there is no weak phase in the interface layer. It is found by electron probe microanalysis (EPMA) that cobalt diffuse into the coating,which is helpful to enhance the bonding strength between the substrate and the coating.