Influence of laser re-melting and vacuum heat treatment on plasma-sprayed FeCoCrNiAl alloy coatings

FeCoCrNiAl high entropy alloy coatings were prepared by supersonic air-plasma spraying.The coatings were post-treated by vacuum heat treatment at 600 and 900°C,and laser re-melting with 300 W,respectively,to study the influence of different treatments on the structure and properties of the coatings.The phase constitution,microstructure and microhardness of the coatings after treatments were investigated using X-ray diffraction,scanning electron microscopy and energy dispersive spectrometry.Results showed that the as-sprayed coatings consisted of pure metal and Fe-Cr.The AlNi_3 phase was obtained after the vacuum heat treatment process.A body-centered cubic structure with less AlNi_3 could be found in the coating after the laser re-melting process.The average hardness values of the as-sprayed coating and the coatings with two different temperature vacuum heat treatments and with laser re-melting were 177,227,266 and 682 HV,respectively.This suggests that the vacuum heat treatment promoted the alloying process of the coatings,and contributed to the enhancement of the coating wear resistance.The laser re-melted coating showed the best wear resistance.     

Thermal conductivity of plasma-sprayed coatings Ni-Cr-B-Si

Translated from Poroshkovaya Metallurgiya, No. 8(344), pp. 22–23, August, 1991.     

Hydrogen permeability of plasma-sprayed composite alumina-base coatings

Powder Metallurgy and Metal Ceramics -     

Effective area of contact of reinforced plasma-sprayed coatings

Conclusions An expression relating H to and d has been derived, with the aid of which it is possible to select an optimum interfiber spacing in the production of monolayer coatings. The deposit layer height has been found which is necessary for obtaining, after pressing, material of minimum porosity. An angle of inclination of the nozzle has been selected which enables good-quality deposits to be applied to substrates.Translated from Poroshkovaya Metallurgiya, No. 8(224), pp. 39–43, August, 1981.     

反应等离子喷涂TiN涂层电化学腐蚀行为

利用电化学阻抗谱等电化学方法及扫描电镜(SEM)技术,研究了反应等离子喷涂TiN涂层在模拟海水中的电化学腐蚀行为.研究结果表明:TiN涂层的自腐蚀电位高于基体,涂层对基体能起到良好的腐蚀屏蔽作用;腐蚀介质通过涂层的通孔、微裂纹等缺陷渗入涂层与基体的界面腐蚀基体,从而使涂层电阻下降、电容增加,所产生的腐蚀产物在一定程度上可以抑制腐蚀反应的进行,但不会阻止基体局部腐蚀的继续进行.涂层的孔隙是造成涂层电化学腐蚀的主要原因.     

Structural changes in friction surfaces of plasma-sprayed coatings

The features surface morphology are considered for plasma-sprayed coatings used with various counterbodies under conditions of boundary friction. The tribotechnical characteristics of the coatings are examined in relation to the structure. There is found to be a substantial effect from the porosity on the formation of the secondary structures, the changes in topography, and the changes in elemental composition of the friction surface. Institute for Problems of Materials Science, Ukraine National Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 1–2(405), pp. 92–97, January–February, 1999.     

Amplitude dependence of the internal friction of plasma-sprayed coatings

Conclusions An internal friction study of plasma-sprayed coatings has shown that the application of such coatings substantially changes the ADIF parameters (decreases _cr and increases tan ) of a clad specimen. The effects of the dislocation structure of a basis on the physicomechanical properties of a plasma-sprayed coating applied to it have been established.Translated from Poroshkovaya Metallurgiya, No. 2(206), pp. 30–32, February, 1980.