Characterization of WCCo Coatings On Metal Substrates
Characterization of WCCo Coatings On Metal Substrates
Characterization of WCCo Coatings On Metal Substrates
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Center for Biomedical Materials and Engineering,, Harbin Engineering University, Harbin, China
National Key Laboratory for Remanufacturing, Armored Forces Engineering Institute, Beijing, China
Received 14 December 2005; accepted 16 September 2006
Available online 4 October 2006
Abstract
In the present work, WC/Co coatings were obtained by electro-thermal explosion directional spraying technology. The performances including
microstructure, elements distribution, hardness, elastic modulus and wear resistance of the coatings were investigated by means of SEM, EDAX,
nano-indentation test, friction and wear test, respectively. Results show that WC/Co coatings are characterized by compact construction, good
bond, high hardness and elastic modulus. The WC/Co coatings also have outstanding wear resistance.
2006 Elsevier B.V. All rights reserved.
Keywords: Electro-thermal explosion spraying; WC/Co coatings; Performances
1. Introduction
Cermet thermal spraying coatings are widely used in wear
situations because they combine several advantages such as
resistance to abrasion, erosion, corrosive atmospheres and high
temperature [1]. WC/Co is one of the most useful cermet
thermal spraying materials. But for the traditional thermal
spraying technology, it's difficult to gain the high quality cermet
coatings for high porosity and poor bonding of the coatings.
Electro-thermal explosion directional spraying (EEDS),
a new spraying method, will be used widely due to its ability
to process coatings with compact microstructure, high microhardness, low porosity and good bonding. Ushakov [2], and
Tamura [3,4] investigated the characteristics of the EEDS
process. They concluded that the EEDS technique was characterized by the duration of process of between 1 and 10 ms, a
plasma temperature about 104 K, the speed of spraying particles
up to 34.5 km/s, and an average cooling rate of particles up to
109 K/s.
Few researches have been done on the microstructure and
tribological properties of EEDS coatings. Tamura studied the
Corresponding author. National Key Laboratory for Remanufacturing,
Armored Forces Engineering Institute, Beijing, China. Tel.: +86 451 82518173.
E-mail address: jg97721@yahoo.com.cn (G. Jin).
0167-577X/$ - see front matter 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.matlet.2006.09.036
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Table 1
EDAX results of WC/Co coatings
Element (wt.%)
Fe
Area A
Area B
37.73
22.55
57.13
65.23
5.14
12.22
Fig. 1. SEM micrographs of WC/Co coatings. (a) Coating area and (b) transition
area.
was 0.42 m/s, and the sliding time varied from 10 min to 60 min.
The variation of friction coefficient with sliding time was
recorded automatically. The width of worn scar was measured
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4. Conclusions
Microstructure observations show that the coatings possess
such good properties as compact microstructure, low content of
oxidation and decomposition, high microhardness and good
bond. In the transition area, the diffusion of W, Fe and C is
obvious and there exist the columnar grain and isometric crystal.
The two phenomena show that the bond between the coating and
substrate is a metallurgical and diffusive one. The microhardness
and elastic modulus is high for the fine grain strengthening. The