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The Cr3C2 thermal spray coating on Al-Si substrate

Richert M., Książek M., Leszczyńska-Madej B., Nejman I., Grzelka R., Pałka P.

Journal of Achievements in Materials and Manufacturing Engineering

2010

Vol. 38, nr 1

95-102

Purpose: The objective of this work was to present the changes between the plasma sprayed and high velocity oxy-fuel (HVOF) wear Cr3C2 resistant coats. The differences in microstructure and microhardness of coatings were investigated. The characterization of fully melted, un- melted and partly melted areas was performed. Design/methodology/approach: The investigated coats contained very differentiate areas, especially plasma sprayed layers. Systematic investigations of microstructure by using optical, electron scanning microscopy and transmission electron microscopy selected fully melted, un- melted or partly melted areas and their characteristic features were performed. Microhardness of coats was measured and compared with the similar literature results. Findings: Microstructure of plasma sprayed coats was finding as consisting from elongating splats, additionally contained un-melted previous particle of powder and some voids and oxides. Contrary to this the HFOV coatingss were more uniform containing almost equiaxial grains. The microhardness of HFOV coatings was almost two times higher than plasma sprayed ones. Practical implications: The performed investigations provide information, which could be useful in the industrial practice about the essential features of wear resistant plasma sprayed coatings. Originality/value: It was assumed that HVOF coatings have more uniform microstructure, higher microhardness, which could suggests better resistance before the wear and grindability.

Experimental investigation of effects of external loads on erosive wear

Imrek H., Bagci M., Khalfan O. M.

Journal of Achievements in Materials and Manufacturing Engineering

2009

Vol. 32, nr 1

18-22

Purpose: The purpose of the paper is to investigate effects of external loads on erosive wear. Design/methodology/approach: In this experimental study, specimens were placed on specially designed a specimen holder and then, external tensile loads corresponding to 0%, 20%, 40% and 60% of the specimen’s yield strength were applied on the specimens. For every load step, the specimens were subjected to 15ş, 30ş, 45ş, 60ş, 75ş and 90ş of erodent impact angles. At the end of the tests, effects of external loads and impingement angles on erosive wear were studied. In the experimental set, dry and compressed air was used to impinge erodents onto the test specimens and subsequent wear was investigated. During the tests, the impingement angles were adjusted by turning the specimen holder around its axis. Erodent particles used were SAE G40 having internal uniform martensitic structure and angular geometry. Determination of erodents speed was achieved with the help of the Rotating Double Disc Method. The speed used in the tests was 30 m/s. Findings: At the end of the tests, erosive wear rates were obtained as functions of stresses and impingement angles. Graphs showing variations of erosive wear rates for load values obtained against every impingement angle and yield stress were drawn. Critical impingement angle and load values at which maximum erosion rate was obtained were determined. Research limitations/implications: In researches made on erosive wears so far; there are only few studies dealing with the effects of external loads on the specimens subjected to erosive wear. By considering that stresses may affect the erosive wear, the stress state around contact area as well as material properties, this experimental study has thus, investigated likely effects of stresses on the erosive wear. With the help of the designed special specimen holder, the specimens were subjected to tensile stresses that are lower than the yield strength of the material and then the erosive wear was investigated. Originality/value: The investigations of effects of external loads on erosive wear.