Alumina coated cutting tool
AssigneeSandvik AB
InventorBjorn Ljungberg
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Abstract
A body with a coating comprising one or more refractory layers of which at least one layer is a layer of .alpha.-Al.sub.2 O.sub.3 textured in the (110)-direction is disclosed. Said alumina layer which is essentially free of cooling cracks, comprises platelike grains with a length of 2-8 .mu.m and a length/width ratio of 1-10, preferably 3-7. The coated tools according to the presently claimed invention show improved tool lives compared to prior art tools when used for machining steel or cast iron material.
Claims12
A coated body with a <20 .mu.m thick coating including at least one layer of alumina with a thickness of 1-10 .mu.m, said coated body having a thermal expansion coefficient between 4 and 7.multidot.10.sup.-6 K.sup.-1 said alumina layer being essentially free of cooling cracks, said alumina layer comprising flat grains with a length of 2-8 .mu.m and a length/width ratio of 1-10 and having a single phase .alpha.-structure textured in the (110)-direction with a texture coefficient larger than 1.5, the texture coefficient being defined as below:
- ##EQU2## where I(hkl)=measured intensity of the (hkl) reflection
- I.sub.o (hkl)=standard intensity of the ASTM standard powder pattern diffraction data
- n=number of reflections used in the calculation, (hkl)
- reflections used are:
- (012), (104), (110), (113), (024), (116).
Dependencies are inferred from the claim text.