Precursor influence on tribological properties of metal-ceramic composites designed for aviation machine parts
Andrzej Posmyk, Jerzy Myalski
Quarterly No. 1, 2015 pages 16-20
DOI:
keywords: hybrid composite, structure, precursor, glassy carbon, tribological properties, solid lubricant
abstract The paper presents the influence of the chemical composition and structure of a glassy carbon precursor on the tribological properties of a metal-ceramic composite, manufactured with the application of this precursor. Two groups of composites containing two different carbon precursors have been manufactured and studied. The first composite contained a glassy carbon precursor embedded from the liquid state in a porous ceramic foam with 90% open porosity. The ceramic foam (Al2O3) is the reinforcing phase and the glassy carbon functions as a solid lubricant. A twofold increase in compressive strength was observed when the foam was present. The foam porosity was reduced to 85% after it was coated with carbon. However, it was good enough for proper infiltration with the liquid matrix alloy. In the case of the second composite, it is a spatial skeleton made of glassy carbon (RCV) which functions both as the reinforcement and solid lubricant. The open porosity of the carbon foam (95%) promoted good infiltration with the matrix alloy. There was no report of holes which were not filled with the matrix alloy within the entire volume of the samples subjected to microscopic tests. The wettability of the foam surface with the matrix alloy is sufficient enough to form strong bonds. The composite containing ceramic foam coated with glassy carbon showed better tribological properties than the composite which contained only carbon foam.