Accession Number : AD0634361

Title :   CHEMICAL STRENGTHENING OF CERAMIC MATERIALS.

Descriptive Note : Summary rept., 7 Apr 65-6 Apr 66,

Corporate Author : LINDEN LABS INC STATE COLLEGE PA

Personal Author(s) : Kirchner, Henry P. ; Gruver,Robert M. ; Walker,Ralph E.

Report Date : 07 MAY 1966

Pagination or Media Count : 139

Abstract : An investigation of the effect of compressive surface layers on the strength of polycrystalline ceramic bodies is described. Low expansion surface layers were formed on polycrystalline ceramics by chemical reactions at high temperatures. During cooling after sintering, the main body tends to contract more than the surface layers leading to compressive stresses in the surfaces. Failure, by shearing of the surface layers, was prevented by establishing gradual variations in composition within the body. These variations in composition result in variations in expansion coefficient which, in turn, result in gradual variations in stresses and reduction of the maximum shear stress in the surface layer. The compressive stresses may act to reduce the contribution of surface flaws to the structural failure of these bodies. Chemical strengthening was attempted with alumina, titania, spinel, magnesia, forsterite, steatite, nickel oxide and zirconia bodies and was achieved for the first six materials named. The experiments with nickel oxide and zirconia gave unreliable results. (Author)

Descriptors :   (*CERAMIC MATERIALS, *HEAT TREATMENT), (*SURFACE PROPERTIES, CERAMIC MATERIALS), THERMAL EXPANSION, THERMAL STRESSES, SHOCK RESISTANCE, DEFORMATION, THERMAL PROPERTIES, ALUMINUM COMPOUNDS, OXIDES, SILICATES, TITANIUM COMPOUNDS, SPINEL, MAGNESIUM COMPOUNDS, NICKEL COMPOUNDS, ZIRCONIUM COMPOUNDS, CASE HARDENING, CERAMIC COATINGS, SOLID SOLUTIONS, PRECISION FINISHING, FLUORINATION, SINTERING, TOUGHNESS, COMPRESSIVE PROPERTIES

Subject Categories : Ceramics, Refractories and Glass

Distribution Statement : APPROVED FOR PUBLIC RELEASE