新型陶瓷涂层硬质合金刀具的涂层机理和切削性能

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，从而为涂层刀具制造展示了一种全新的涂层方法。使用浸渍提拉法对刀具基体进行涂层，然后经凝胶、干燥和1200℃热处理后可以得到厚度适宜的α－Al2O3涂层，涂层完整，无宏观缺陷，并且在初步的切削试验中显示出一定效果。涂层在1140℃左右转化成α－Al2O3，在1200℃烧结致密，而在1250℃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。切削试验的结果表明，所得涂层能有效地阻止前刀面上的粘结磨损，从而提高了刀具的使用寿命。

COATING MECHANISM AND CUTTING PERFORMANCE OF NOVEL CERAMIC COATED CARBIDE

Ceramic coated cemented carbide cutting tools are prepared from aluminum alkoxide solution and carbide substrates by sol gel ro ute. The carbide substrates is coated with boehmite sol by dip coating process and d ried to get gel film. After the heat treatment at 1200℃, the coating with a thi ckness up to 10μm could be obtained without any macroscopic defect and showed g ood performance in turning medium carbon steel, which presented a novel and prom ising coating method for cutting tools. The results suggested that the coating c onvert to α alumina at about 1140℃ and sintered to relatively high density at 1200℃. The coating is polycrystalline and isotropic and there is in weak phase in the interface layer. It is found that cobalt diffused into the coating, which would be conductive to enhance the bonding strength between the substrate and t he coating.