DETONATION SPRAYED COATINGS OF (Ti, Cr)B2–NiAlCr COMPOSITE MATERIALS
І. DEPOSITION TECHNIQUE AND COMPOSITION AND MICROSTRUCTURE OF COATINGS

  
О.A.Bondarenko 1,
 
K.М.Galtsov 1,
 
A.Leitans 2,
 
I.Boiko 2,
  

1 I. M. Frantsevich Institute for Problems of Materials Science of the NAS of Ukraine, Omeliana Pritsaka str.,3, Kyiv, 03142, Ukraine
2 Рижский Технический университет, ул. Кипсалас, 6Б, Riga, LV 1048
akwa@ukr.net

Powder Metallurgy - Kiev: Frantsevich Institute for Problems of Materials Science NASU, 2020, #05/06
http://www.materials.kiev.ua/article/3089

Abstract

Coatings from (Ti, Cr)B2–NiAlCr cermet materials were deposited on structural steel by detonation spraying. The optimal spraying modes depending on the ratio of structural components were determined for the developed materials. The effect from the content of refractory and metal components in the sprayed material on the microstructure and coating composition was examined. A heterophase lamellar microstructure with a fairly uniform phase distribution was formed. Coatings of materials with a greater content of the metal component have more uniform phase distribution, which largely depends on the process characteristics of the powders. Powders based on the NiAlCr alloy have three to four times higher flowability than powders based on (Ti, Cr) B2, which promotes more stable powder supply and the spraying process as a whole. Therefore, the coatings have higher density and more uniform phase distribution. Various coating designs were used: without a sublayer, with a sublayer from a NiCr detonation coating, and with a sublayer produced by electrospark deposition with the same material as used for the base coating. The resultant coatings have high-quality adhesive contact with the substrate, both with and without a NiCr detonation sublayer, and their thicknesses can reach 0.8–1 mm. When a sublayer from an electrospark coating with a high (Ti, Cr)B2 content was used, cracks were found at the coating–sublayer boundaries. This is due to higher hardness of the sublayer and the deterioration of its deformation under the action of accelerated particles of the sprayed material. Preliminary surface preparation by spraying different types of sublayers hardly influences the microstructure of the coatings and the quality of their contact with the substrate.


COATING, COMPOSITE CERMET MATERIALS, DETONATION-SPRAYED COATING, MICROSTRUCTURE, TITANIUM–CHROMIUM DIBORIDE