Zirconia ceramics and method for producing same

• US 4,977,114 A
• Filed: 11/17/1989
• Issued: 12/11/1990
• Est. Priority Date: 11/28/1986
• Status: Expired due to Fees

• Current Assignee: Sumitomo Chemical Company Limited
• Original Assignee: Sumitomo Chemical Company Limited
• Inventors: Maeda, Katsuya, Horinouchi, Kazuo
• Primary Examiner(s): Dixon, Jr., William R.
• Assistant Examiner(s): JONES, DEBORAH D
• Application Number:
  US07/438,946
• Time in Patent Office: 389 Days
• Field of Search: 501/103, 501/104, 264/66
• US Class Current: 501/104
• CPC Class Codes: C04B 35/486 Fine ceramics

Abstract

Disclosed are zirconia ceramics superior in mechanical strength, hardness and toughness and a method for producing them. The zirconia ceramics contain ca. 7-12 mol % of cerium oxide and ca. 2-7 mol % of magnesium oxide and have an average crystal grain size of crystal grains thereof of 1 μm or less, at least ca. 80 mol % of the crystal grains being tetragonal grains and the balance being monoclinic grains, and have a bending strength of at least 100 kg/mm², a fracture toughness of at least 10 MNm^-1.5 and a Vickers hardness of at least 1000 kg/mm². The method comprises calcining a hydrate obtained by coprecipitation method from water-soluble salts of cerium and magnesium and a basic salt of zirconium or a hydrate obtained by adding water-soluble salts of cerium and magnesium to a zirconium hydrate and neutralizing the mixture of hydrates, further grinding the calcined hydrate to obtain zirconia powders of 1 μm or less in average crystal grain size, then shaping the powders and sintering the resulting shaped product.

Claims

1. Zirconia ceramics which contain 7-12 mol% of cerium oxide and 2-7 mol% of magnesium oxide and which have an average crystal grain size of 1 μ

m or less, at least 80 mol% of the crystal grains being tetragonal grains and the balance being monoclinic grains, and have a bending strength of at least 100 kg/mm², a fracture toughness of at least 10 Mnm^-1.5 and a Vickers hardness of at least 1000 kg/mm².

2. A method for producing zirconia ceramics consisting essentially of about 7-12 mol% of cerium oxide and about 2-7 mol% of magnesium oxide, having an average crystal grain size of 1 μ

m or less, at least about 80 mol% of the crystal grains being tetragonal grains and the balance being monoclinic grains and having a bending strength of at least 100 kg/mm², a fracture toughness of at least 10 Mnm^-1.5 and a Vickers hardness of at least 1000 kg/mm² which comprises calcining a hydrate obtained by coprecipitation from water-soluble salts of cerium and magnesium and a basic salt of zirconium which are prepared so as to give the above-mentioned compositions after sintering or a hydrate obtained by adding water-soluble salts of cerium and magnesium to a zirconium hydrate which are also prepared so as to give the above-mentioned compositions after sintering and neutralizing the mixture of hydrates, further grinding the calcined hydrate to obtain zirconia powders of 1 μ

m or less in average crystal grain size, then shaping the powders and sintering the resulting shaped product.