Characterization of Fe-Cr-B based coatings produced by HVOF and PTA processes

Abstract

Two Fe-Cr-B based gas atomized powders, Armacor M and 16, were thermally sprayed on a low carbon steel substrate, using the HVOF (High Velocity Oxygen Fuel) process. Armacor M was also weld-surfaced with the PTA (Plasma Transferred Arc) process. The resultant deposits were subsequently characterized, using X-ray diffraction, scanning electron microscopy, and microhardness measurement. The effects of heat treatment were also studied for HVOF-sprayed coatings. The wear performance of the coatings was investigated by two-body abrasive wear tests. The results of microstructural analysis of as-sprayed deposits revealed oxide and boride phases such as Fe304 and Crl.65Feo.35Bc~.~, in an ~ matrix for the HVOF-sprayed Armacor 16 coating, and only the boride phases (Cr1.65F%35B0.~6 and Cr~B) in an tx matrix for the HVOFsprayed Armacor M coating. PTA weld-surfaced Armacor M coating contains needle-type long precipitates of Cr~B and Crl.65Fe0.3~B~).9~, in the a matrix. The hardness of the HVOF-sprayed Armacor 16 coating after heat treatment was substantially less than that of the as-sprayed coating due to the phase transformation from tx to y phase. Heat treatments of the HVOF-sprayed Armacor M coating did not produce changes in phase and its hardness decreased as compared to that of the as-sprayed coating. While HVOF-sprayed and PTA weld-surfaced Armacor M coatings have the same hardness, the latter shows better abrasive wear resistance because of the size and orientation of its boride phases. The broadening of the XRD patterns and the increase in hardness after wear testing suggest that the transformation from the crystalline to the amorphous structure occurred on the uppermost layer during wear testing.

Tribology of a Fe–Cr–B-Based Alloy Coating Fabricated by a Controlled Short-Circuit MIG Welding Process

“…For similar Fe-Cr-B-based alloys, it has been reported the boride phase particles as (Cr,Fe) 2 B [2,3]. The formation of the BCC solid solution phase is also consistent with the reported results [2,5,6,[9][10][11]14].…”

“…Wear protection can be provided by metal matrix composites (MMCs), which are multiphase materials composed of hard reinforcing particles embedded in a metallic matrix [1]. One of these systems is the Fe-Cr-B-based alloys that contain hard boride particles, namely (Cr,Fe) 2 B, (Cr,Fe) x B, Cr 2 B, Fe 1.1 Cr 0.9 B 0.9 , and/or Cr 1.65 Fe 0.35 B 0.96 , dispersed in a Fe-based solid solution matrix [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. This system has been shown to exhibit excellent resistance against sliding and abrasive wear [6,7].…”

“…The Fe-Cr-B-based alloys have commonly been applied as a coating using thermal spray processes, such as detonation gun [7,14] and high velocity oxygen fuel (HVOF) [4-6, 11, 13]. Plasma-transferred arc (PTA) welding process has also been successfully used to fabricate a coating that provides a stronger metallurgical bond between the coating and the substrate and exhibits higher wear resistance when compared to thermal spray processes [11][12][13].…”

Optimization of the Deposition Parameters of HVOF FeMnCrSi+Ni+B Thermally Sprayed Coatings

“…The levels defined in this experiment are based on the values recommended by manufacturers [17], as well as articles where similar alloys deposited by HVOF were studied [18][19][20][21][22][23][24][25][26][27]. Table 2 shows the L9 orthogonal array with the factors and levels used in this article.…”

Property improvement of stainless-steel-base surface composites fabricated by high-energy electron-beam irradiation

“…In order to improve its wear resistance, lubrication and surface coating methods are presently used. However, their applications are still limited because the lubrication cannot be used at high temperatures and the surface coated layer can be easily separated during operation [1,2].…”