Accession Number : ADA317563

Title :   Ceramic Bearing Development. Volume 4. Tribochemical Finishing of Silicon Nitride.

Descriptive Note : Interim rept. 1 Aug 92-1 Oct 94,

Corporate Author : CERBEC INC EAST GRANBY CT

Personal Author(s) : Hah, S. R. ; Fischer, Traugott E. ; Burk, Charles

PDF Url : ADA317563

Report Date : MAR 1995

Pagination or Media Count : 115

Abstract : Tribochemical finishing of silicon nitride was developed by the Tribology Research Group at the Stevens Institute of technology. The finishing process produces ultrasmooth surfaces without mechanical defects. Over 40 chemical solutions such as acids, bases, salts, inorganic and organic oxidizers were tested. Distilled water shows high volume removal rates but some solid wear debris are produced by surface fracture. Hydrogen peroxide, at 3% or higher concentrations, produces high volume removal rates and pure tribochemical reaction. Chromic(VI) acid in all concentrations shows the best, purely tribochemical polishing results. Combinations of chromic oxides and hydrogen peroxides, also many of the chromates(VI) show outstanding efficiencies. Tribochemical polishing produces defect free, ultra smooth surfaces with Ra = 0.5 nm (0.02 micro-in) at 50 micrometers (0.002 in) cut-off, 2.0 nm (0.08 micro-in) at 0.8 mm (0.032 in) cut-off and 4.0 nm (0.16 micro-in) at 8 mm (0.320 in) cut-off . Stainless steel and cast iron are effective tool materials for the tribochemical polishing of silicon nitride. Tribochemical polishing is easily adapted to most industrial finishing processes with minimal cost.

Descriptors :   *SURFACE FINISHING, *SILICON NITRIDES, X RAY DIFFRACTION, SURFACE ROUGHNESS, STAINLESS STEEL, FRACTURE(MECHANICS), CERAMIC MATERIALS, DEFECTS(MATERIALS), RESIDUAL STRESS, SURFACE CHEMISTRY, CONCENTRATION(CHEMISTRY), TRIBOLOGY, POLISHING, CHROMIC ACID, HYDROGEN PEROXIDE, BALL BEARINGS.

Subject Categories : Physical Chemistry
      Coatings, Colorants and Finishes
      Ceramics, Refractories and Glass

Distribution Statement : APPROVED FOR PUBLIC RELEASE