This paper exhibits an outline of the piston rings operational characteristics and consequently, of their main functional challenges. The basic geometrical shapes, materials and manufacturi...

Tribological solutions for engine piston ring surfaces: an overview on the materials and manufacturing

IN view of the extreme interest being taken throughout the industrial world in the production of articles made from sintered metallic powders, a survey of existing knowledge of the fundamental principles involved is very much to be desired. Much of this information has been revealed by research, and the time has come when it should be collected and critically discussed. Principles of Powder Metallurgy By Franz Skaupy. Translated by Dr. Marion Lee Taylor. Pp. 80. (New York: Philosophical Library, Inc., 1944.) 3 dollars.

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Principles of Powder Metallurgy

Effect of different oxides addition on the thermal expansion coefficients and residual stresses of Fe-based diamond composites

The paper presents the experiments on adding rare-earth element cerium to diamond matrix composites. Based on the doping of rare earth in metal powders including tungsten carbide, a small amount of nickel, iron entirely replacing cobalt in diamond matrix and the process route of rare earth doping is indicated. The performance of matrix composites with and without rare-earth elements has been assessed. The results obtained show that the flexural strength, the hardness, and the impact ductility of matrix composites with rare-earth elements have been improved. The flexural strength and the impact ductility increased correspondently by 10–62% and about 5, as compared to composites free of rare-earth elements. Rare-earth diamond tool matrix composites where Co was r’eplaced with Fe, which provides a good practical service performance and a low price, have been successfully studied, corresponding diamond bits and saw blades have been manufactured.

/pdf/doping-fe-based-diamond-tool-matrix-composites-with-a-rare-zi6v3war34.pdf

Doping Fe-based diamond tool matrix composites with a rare-earth element

This paper makes the experimental experiment on adding rare earth elements cerium doped in diamond matrix composites. Based on the doping of rare earth in metal powders including tungsten carbide, iron and nickel, the cobalt in diamond matrix is entirely with iron and the process route of rare earth doping is indicated. The performance of matrix composites with rare earth elements and free of rare earth elements is measured and the results obtained show that the flexural strength, the hardness and the impact ductility of matrix composites with rare earth elements are improved and the flexural strength increases by 10~62% over that of the composites free of rare earth elements, and the impact ductility by about 5% correspondently. We have successfully studied out the rare-earth diamond tool matrix composites replacing Co with Fe, bearing good practical service performance and low price, and have made corresponding diamond bit.

Experiment on Doping Rare Earth Diamond Tools Matrix Composites with Fe Replacing Co

An analytical densification model describing the final stages of hot pressing and sintering has been developed and found to be consistent with empirical findings. The behaviour of composite powders for the matrices of diamond tools has been studied under hot pressing conditions. Differential scanning calorimetry was used to determine the heat capacity at constant pressure C p of pure Co, 663Cu, and composite iron- and cobalt based powders (also containing WC, Ni and 663Cu). The relationship between C p and composite densification has been analysed, and it has been found that optimised rare earth additions to the iron based composite powders can produce C p characteristics close or equivalent to that of pure Co powders. This modified composite powder has been used to hot press diamond drill and saw bits that show good properties. Employing a densification regime guided by the dynamic model has been found radically to improve stability in service (bend strength, hardness, impact, ductility and poro...

D.-Y. Zhang

Papers

Thermophysics characteristics and densification of powder metallurgy composites