PROCESS FOR PRODUCING AN ALUMINA COATING COMPOSED MAINLY OF a-TYPE CRYSTAL STRUCTURE

A clad member excellent in wear resistance and heat resistance comprising an alumina coating comprised mainly of α-type crystal structure formed on the surface, said alumina coating being produced by a comprising, when forming an alumina coating composed mainly of α-type crystal structure on a base material having a primary coating preliminarily formed thereon, forming a hard coating composed of a metal component containing Al and Ti as unavoidable elements and a compound of B, C, N, O, etc. As said primary coating, oxidizing said hard coating composed mainly of α-crystal structure on said oxide-containing layer.

20-28. (canceled)

A process for producing a member clad with an alumina coating comprised mainly of α-type crystal structure, comprising successively executing a process for forming at least any one of the following coatings (a)-(c) as an intermediate layer, a process for oxidizing the surface of said intermediate layer, and a process for forming an alumina coating comprised mainly of α-type crystal structure within the same apparatus:

• (a) A coating comprised of a pure metal or alloy:
• (b) A coating comprised mainly of a metal solid-dissolving nitrogen, oxygen, carbon or boron:
• (c) A coating comprised of a metal nitride, oxide, cemented carbide or boride containing nitrogen, oxygen, carbon or boron insufficient to a stoichiometric composition.

A process for producing a member clad with an alumina coating comprised mainly of α-type crystal structure, comprising successively executing a process for forming a primary coating on a base material, a process for forming at least any one of the following coatings (a)-(c) on the surface of said primary coating as an intermediate layer, a process for oxidizing the surface of said intermediate layer, and a process for forming an alumina coating comprised mainly of α-type crystal structure within the same apparatus:

• (a) A coating comprised of a pure metal or alloy:
• (b) A coating comprised mainly of a metal solid-dissolving nitrogen:oxygen, carbon or boron:
• (c) A coating comprised of a metal nitride, oxide, cemented carbide or boride containing nitrogen, oxygen, carbon or boron insufficient to a stoichiometric composition.

A process for producing an alumina coating comprised mainly of α-type crystal structure on a sintered cBN base material comprised of a binder phase and a cubic boron nitride dispersed layer, comprising oxidizing the surface of said sintered cBN base material, and then forming an alumina coating.

A member clad with an alumina coating comprised mainly of α-type crystal structure which is a clad member comprising a sintered cBN comprised of a binder phase and a cubic boron nitride dispersed phase, and an alumina coating of α-type crystal structure applied thereto, said member further comprising an oxide-containing layer interposed in the interface between said sintered cBN base material and said alumina coating.

A process for producing a member clad with an alumina coating comprised mainly of α-type crystal structure, comprising, when producing a clad member comprising a sintered cBN comprised of a binder phase and a cubic boron nitride dispersed phase clad with an alumina coating comprised mainly of α-type crystal structure, successively executing a process for oxidizing the surface of said sintered cBN and a process for forming said alumina coating comprised mainly of α-type crystal structure within the same deposition apparatus.

40-44. (canceled)

A process for producing a member clad with an alumina coating comprised mainly of α-type crystal structure, comprising successively executing a process for forming a primary coating on a base material, a process for gas ion-bombarding the surface of said primary coating, a process for oxidizing the resulting surface, and a process for forming an alumina coating comprised mainly of α-type crystal structure within the same apparatus.

47-50. (canceled)

A member clad with an alumina coating comprised mainly of α-type crystal structure comprising an alumina coating comprised mainly of α-type crystal structure formed on a base material (including also a base material having a primary coating preliminarily formed thereon), wherein a concentration gradient layer in which the concentration of a metal used for a metal ion bombardment treatment is gradually increased toward the surface layer side is present in the vicinity of the surface of said base material, and an oxide-containing layer and said alumina coating comprised mainly of α-type crystal structure are formed successively on the surface side of said concentration gradient layer.

A process for producing a member clad with an alumina coating comprised mainly of α-type crystal structure, comprising successively executing a process for metal ion-bombarding the surface of a base material, a process for oxidizing the resulting surface, and a process for forming an alumina coating comprised mainly of α-type crystal structure within the same apparatus.

A process for producing a member clad with an alumina coating comprised mainly of α-type crystal structure, comprising successively executing a process for forming a primary coating on a base material, a process for metal ion-bombarding the surface of said primary coating, a process for oxidizing the resulting surface, and a process for forming an alumina coating comprised mainly of α-type crystal structure within the same deposition apparatus.

56-66. (canceled)

A clad member excellent in wear resistance and heat resistance comprising an alumina coating comprised mainly of α-type crystal structure formed on the surface, said alumina coating being produced by a process comprising, when forming an alumina coating composed mainly of α-type crystal structure on a base material having a primary coating preliminarily formed thereon, forming a hard coating composed of a metal component containing Al as an unavoidable element and a compound of B, C, N, O, etc. as said primary coating, oxidizing said hard coating to form an oxide-containing layer, and then forming an alumina coating composed mainly of α-type crystal structure on said oxide-containing layer.

A clad member excellent in wear resistance and heat resistance comprising an alumina coating comprised mainly of α-type crystal structure formed on the surface, said alumina coating being produced by the process comprising, when forming an alumina coating composed mainly of α-type crystal structure on a base material having a primary coating preliminarily formed thereon, forming a hard coating composed of a metal whose standard free energy for oxidation generation is greater than that of aluminum and a compound of B, C, N, O, etc. as said primary coating, oxidizing said hard coating to form an oxide-containing layer, and then forming an alumina coating composed mainly of α-type crystal structure on said oxide-containing layer.

A clad member excellent in wear resistance and heat resistance comprising an alumina coating comprised mainly of α-type crystal structure formed on the surface, said alumina coating being produced by the process comprising, when producing an alumina coating composed mainly of α-type crystal structure on a base material (including a base material having a primary coating preliminarily formed thereon), forming at least one of the following coatings (a)-(c) prior to the deposition process of alumina, oxidizing the resulting surface, and then forming an alumina coating:

• (a) a coating composed of a pure metal or alloy:
• (b) a coating composed mainly of a metal solid-dissolving nitrogen, oxygen, carbon or boron:
• (c) a coating composed of a metal nitride, oxide, cemented carbide or boride containing nitrogen, oxygen, carbon or boron insufficient to a stoichiometric composition.