Alumina-coated sintered body

US5674564A · kind A · utility

Assignee

• SANDVIK AB · SE

Inventors

• Bjorn Ljungberg · Stuvsta-Snättringe, SE
• Mats Sjostrand · Sollentuna, SE
• Jan N. Lindstrom · Knivsta, SE

Key dates

• Filing date: May 30, 1995
• Grant date: Oct 7, 1997
• Expiry date: May 30, 2015

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02T50/60
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

A sintered hard material body is 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 (.O slashed.) in .mu.m for which: EQU .O slashed..ltoreq.kx+a where PA1 x is coating thickness in .mu.m on at least 80% of the flat surface of the body, PA1 k=0.5, preferably 0.3, and PA1 a=2 .mu.m for 4.ltoreq.x<20 and a=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 hydrolyzing 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.degree.-1000.degree. C., preferably 850.degree.-970.degree. C., and the volume concentration of the additional reactant is 0.25-3%, preferably 0.3-1%, of the total gas volume.