Abrasive grain comprising manganese oxide
AssigneeMinnesota Mining and Manufacturing Company
InventorsWilliam P. Wood, Henry A. Larmie
Life of this patent
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Abstract
Abrasive grain including manganese oxide therein are provided. The inclusion of manganese oxide can be utilized to reduce the transition temperature of transitional alumina(s) to alpha alumina(s), during the formation of the abrasive grain. Further, manganese oxide presence can be utilized to generate sintered abrasive grain having a submicrometer, faceted microstructure. The abrasive grain are useful in abrasive articles such as coated abrasives, three-dimensional, low density abrasives, and bonded abrasives.
Claims51
An abrasive grain comprising a ceramic alpha alumina-based material (i) having an alpha alumina submicrometer, faceted microstructure and (ii) having therein:
- (a) at least 0.1 percent by weight manganese oxide;
- and
- (b) at least 0.1 percent by weight oxide selected from the group consisting of zirconium oxide, yttrium oxide, lanthanum oxide, neodymium oxide, cerium oxide, praseodymium oxide, samarium oxide, gadolinium oxide, erbium oxide, ytterbium oxide, dysprosium oxide, europium oxide, hafnium oxide, and mixtures thereof,
- based on the total weight of said ceramic alpha alumina-based material, wherein said manganese oxide and said oxide of (b) are collectively present in an amount sufficient to provide an abrasive grain having an average hardness of at least 19 GPa.
An abrasive grain comprising a ceramic alpha alumina-based material including manganese oxide in the range from 0.1 to about 10 percent by weight and rare earth oxide in the range from 0.1 to about 10 percent by weight, based on the total weight of said ceramic alpha alumina-based material, wherein said manganese oxide and said rare earth oxide are collectively present in an amount sufficient to provide an abrasive grain having an average hardness of at least 19 GPa.
A method for making alpha alumina-based ceramic abrasive grain, said method comprising the steps of:
- (a) providing an alpha alumina-based ceramic precursor comprising alpha alumina precursor, manganese material, and nucleating material;
- and
- b) heating said ceramic abrasive grain precursor to a sintering temperature that is at least 20.degree. C. less than the sintering temperature of a comparable alpha alumina-based ceramic precursor that is essentially free of manganese material, for a time sufficient to provide alpha alumina-based ceramic abrasive grain having a density of at least 95 percent of theoretical and alpha alumina crystallites having an average crystallite size of less than 1 micrometer.
A method of making alpha alumina-based ceramic abrasive grain, said method comprising the steps of:
- (a) providing an alpha alumina-based ceramic abrasive grain precursor comprising an amount of manganese material effective to reduce the transitional alumina to alpha alumina transformation temperature;
- and
- (b) heating said alpha alumina-based ceramic abrasive grain precursor to provide alpha alumina-based ceramic abrasive grain, wherein said heating includes sintering in a non-oxidizing atmosphere.
An abrasive grain comprising a ceramic alpha alumina-based material having an alpha alumina submicrometer, faceted microstructure and consisting essentially of alpha alumina, manganese oxide, and zirconium oxide, wherein said submicrometer, faceted microstructure is provided by the presence of:
- (a) alumina;
- (b) at least 0.1 percent by weight manganese oxide;
- and
- (c) at least 0.1 percent by weight zirconium oxide, based on the total weight of said ceramic alpha alumina-based material, said ceramic alpha alumina-based material having a density of at least 90 percent of theoretical.
A method of making an abrasive grain comprising a ceramic alpha alumina-based material having a density of at least 90 percent of theoretical and an alpha alumina submicrometer, faceted microstructure provided by the presence of (i) alumina, (ii) at least 0.1 percent by weight manganese oxide, and (iii) at least 0.1 percent by weight secondary oxide selected from the group consisting of zirconium oxide, yttrium oxide lanthanum oxide, neodymium oxide, cerium oxide, praseodymium oxide, samarium oxide, gadolinium oxide, erbium oxide, ytterbium oxide, dysprosium oxide, hafnium oxide, and mixtures thereof, based on the total weight of said ceramic alpha alumina-based material, said method comprising the steps of:
- (a) providing an alpha alumina-based ceramic abrasive grain precursor comprising (A) manganese material and (B) secondary oxide precursors thereof, and mixtures thereof;
- and
- (b) heating said alpha alumina-based ceramic abrasive grain precursor to provide said alpha alumina-based ceramic abrasive grain.
A method for making alpha alumina-based ceramic abrasive grain, said method comprising the steps of:
- (a) providing an alpha alumina-based ceramic precursor comprising an amount of manganese material effective to reduce the transitional to alpha alumina transformation temperature and a sufficient amount of rare earth material selected from the group consisting of lanthanum oxide, neodymium oxide, cerium oxide, praseodymium oxide, samarium oxide, gadolinium oxide, erbium oxide, ytterbium oxide, dysprosium oxide, precursors thereof, and mixtures thereof;
- and
- (b) heating said alpha alumina-based ceramic abrasive grain precursor to provide alpha alumina-based ceramic abrasive grain comprising at least 0.1 rare earth oxide selected from the group consisting of lanthanum oxide, neodymium oxide, cerium oxide, praseodymium oxide, samarium oxide, gadolinium oxide, erbium oxide, ytterbium oxide, dysprosium oxide, and mixtures thereof, based on the total weight of said alpha alumina ceramic abrasive grain.
Dependencies are inferred from the claim text.