| 摘要 |
<p>According to the invention there is now provided a sintered hard material body at least partly coated with at least one 0.5-20 mu m wear resistant ceramic oxide coating being <80% thicker in the edges than on the flat surfaces. The oxide coating exhibits a grain size ( DIAMETER ) in mu m for which: <MATH> where x is coating thickness in mu m on at least 80% of the flat surfaces of the body, k = 0.5, preferably 0.3 and 1 = 2 mu m for 4</=x<20 and 1=0 for 0.5<x<4. The oxide coating is achieved by using a deposition process in which the body is in contact with a gas containing one or more halides of a metal or metals and a hydrolysing and/or oxidizing agent forming the metal oxides and with an additional reactant (dopant) of sulphur, phosphorus, selenium, tellurium, arsenic, antimony and/or bismuth and/or compounds thereof. The temperature during deposition is in the range of 800-1000 DEG C, preferably 850-970 DEG C, and the volume concentration of the additional reactant is 0.25-3, preferably 0.3-1 % of the total gas volume.</p> |
