Influence of WC Particle Size and Matrix Composition on the Behavior of WC-Co-Cr Coatings Sprayed by the HVOF Process

Author(s):  
J. Berget ◽  
E. Bardal ◽  
T. Rogne

Abstract WC-Co-Cr powders with different WC particle size have been sprayed by the HVOF process. At constant spraying conditions the powders give coatings of different quality. The deposition efficiency during spraying of powders containing large WC particles was found to be low compared to powders with finer WC grains. In addition the amounts of porosity and cracks were different. The coatings have been characterised by different methods. Erosion and erosion-corrosion tests showed that the WC particle size also influence the wear resistance of the coatings. Small WC particle size was found to be beneficial. Chemical composition of the matrix was also found to be decisive for the coating properties. An increase of the chromium content improved the erosion-corrosion resistance.

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 46
Author(s):  
Hu Xu ◽  
Junsheng Sun ◽  
Jun Jin ◽  
Jijun Song ◽  
Chi Wang

At present, most Mo2FeB2-based cermets are prepared by vacuum sintering. However, vacuum sintering is only suitable for ordinary cylinder and cuboid workpieces, and it is difficult to apply to large curved surface and large size workpieces. Therefore, in order to improve the flexibility of preparing Mo2FeB2 cermet, a flux cored wire with 70% filling rate, 304 stainless steel, 60 wt% Mo powder and 40 wt% FeB powder was prepared. Mo2FeB2 cermet was prepared by an arc cladding welding metallurgy method with flux cored wire. In this paper, the microstructure, phase evolution, hardness, wear resistance and corrosion resistance of Mo2FeB2 cermets prepared by the vacuum sintering (VM-Mo2FeB2) and arc cladding welding metallurgy method (WM-Mo2FeB2) were systematically studied. The results show that VM-Mo2FeB2 is composed of Mo2FeB2 and γ-CrFeNi.WM-Mo2FeB2 is composed of Mo2FeB2, NiCrFe, MoCrFe and Cr2B3. The volume fraction of hard phase in WM-Mo2FeB2 is lower than that of VM-Mo2FeB2, and its hardness and corrosion resistance are also slightly lower than that of VM-Mo2FeB2, but there are obvious pores in the microstructure of VM-Mo2FeB2, which affects its properties. The results show that WM-Mo2FeB2 has good diffusion and metallurgical bonding with the matrix and has no obvious pores. The microstructure is compact and the wear resistance is better than that of VM-Mo2FeB2.


2019 ◽  
Vol 33 (01n03) ◽  
pp. 1940019 ◽  
Author(s):  
Weihui Zhang ◽  
Di Cao ◽  
Yanxin Qiao ◽  
Yuxin Wang ◽  
Xiang Li ◽  
...  

Duplex Ni-P-TiO2/Ni coatings were deposited on the brass substrate by using two baths. Ni-P-TiO2 nanocomposite coatings were electroplated as the outer layer on the Ni-plated brass substrate by adding transparent TiO2 sol (0–50 mL/L) into the Ni-P plating solution. The microstructure, mechanical property and corrosion resistance of the duplex Ni-P-TiO2/Ni nanocomposite coatings were systemically investigated. The results show that the interface of duplex coating was uniform and the adhesion between two layers was extremely good. The microhardness of duplex Ni-P-12.5 mL/L TiO2 /Ni coating was [Formula: see text]616 HV[Formula: see text] compared to [Formula: see text]539 HV[Formula: see text] of Ni-P /Ni coating and [Formula: see text]307 HV[Formula: see text] of single Ni coating. Meanwhile, the wear resistance and the corrosion resistance of the duplex nanocomposite coating have also been improved remarkably compared with single Ni coating. However, adding excessive TiO2 sol (more than 12.5 mL/L) caused the agglomeration of TiO2 nanoparticles and led to a porous structure in the outer layer, resulting in the deterioration of coating properties.


Author(s):  
J. Berget ◽  
E. Bardal ◽  
T. Rogne

Abstract Different WC-based coatings have been sprayed by the HVOF process and characterised by different methods. The influence of different powder characteristics on the wear and corrosion performance was investigated. Powder characteristics investigated include: i) average WC particle size, ii) matrix composition and iii) powder grain size distribution. The results show that the coating properties are affected by the different powder characteristics. Small WC particles were found to be beneficial as regards the erosion and erosion-corrosion resistance. An increase of the Cr and Mo content increased the corrosion and erosion-corrosion resistance. Powders with narrow grain size distributions gave coatings of higher quality than powders with wider grain size distributions.


2011 ◽  
Vol 704-705 ◽  
pp. 23-27
Author(s):  
Shu Li Wang ◽  
Ai Qin Wang ◽  
Jing Pei Xie

In this paper ,the WC and high-Cr Cast Iron layer were obtained on the surface of ZG30Cr steel by casting-penetrating process, the organization and wear properties of penetrating layer were studied.The results show that the layer is dense, without pores, slag and other defects, the penetrating layer and substrate are metallurgical bonding. When 30 %WC and 70 % Cr-Fe with 100~120 mesh are added to permeability agent ,the penetrating layer has the best wear resistance, is 6.8 times the matrix materials. Keywords: The layer structure; Particle size; Wear resistance


Author(s):  
T. Rogne ◽  
T. Solem ◽  
J. Berget

Abstract In corrosive media the wear resistance of ceramic-metallic coatings is dependent on the corrosion resistance of the metal matrix. Other factors that will affect the coating deterioration are the corrosivity of the medium and any galvanic interaction from the surrounding material. This paper presents results from a study where different types of WC(Co/Cr/Mo/Ni) powders have been sprayed by HVOF, Diamond Jet 2600 Hybrid equipment. The properties of the sprayed coatings have been verified by metallographic studies and by erosion-corrosion testing both under corrosive and non-corrosive conditions. The results clearly demonstrate the importance of having a metal matrix at least as corrosion resistance as the surrounding materials. When wear exposed components in pipe systems, pumps or valves are coated with a WC type coating, the corrosion resistance of the metal matrix should be compatible to the material of the rest of the system. This is especially important when the surrounding materials are corrosion resistant alloys as stainless steels, where the coatings otherwise will act as an anode.


Author(s):  
T. Ram Prabhu

A wear model is developed based on the discrete lattice spring–mass approach to study the effects of particle volume fraction, size, and stiffness on the wear resistance of particle reinforced composites. To study these effects, we have considered three volume fractions (10%, 20% and 30%), two sizes ([Formula: see text] and [Formula: see text] sites), and two different stiffness of particles embedded in the matrix in a regular pattern. In this model, we have discretized the composite system ([Formula: see text] sites) into the lumped masses connected with interaction spring elements in two dimensions. The interaction elements are assumed as linear elastic and ideal plastic under applied forces. Each mass is connected to its first and second nearest neighbors by springs. The matrix and particles sites are differentiated by choosing the different stiffness values. The counter surface is simulated as a rigid body that moves on the composite material at a constant sliding speed along the horizontal direction. The governing equations are formed by equating the spring force between the pair of sites given by Hooke’s law plus external contact forces and the force due to the motion of the site given by the equation of motion. The equations are solved for the plastic strain accumulated in the springs using an explicit time stepping procedure based on a finite difference form of the above equations. If the total strain accumulated in the spring elements connected to a lump mass site exceeds the failure strain, the springs are considered to be broken, and the mass site is removed or worn away from the lattice and accounts as a wear loss. The model predicts that (i) increasing volume fraction, reducing particle size and increasing particle stiffness enhance the wear resistance of the particle reinforced composites, (ii) the particle stiffness is the most significant factor affecting the wear resistance of the composites, and (iii) the wear resistance reduced above the critical volume fraction ([Formula: see text]), and [Formula: see text] increases with increasing particle size. Finally, we have qualitatively compared the model results with our previously published experimental results to prove the effectiveness of the model to analysis the complex wear systems.


2016 ◽  
Vol 849 ◽  
pp. 671-676 ◽  
Author(s):  
Hao Chen ◽  
Xing Run Ren ◽  
Xue Hui Zhang ◽  
Jin Hui Li

Electroplating Ni-W coatings have been prepared on medium carbon steel substrate by using nickel sulphate and sodium tungstate as precursors. The microstructures, phase compositions and performances of the as-prepared coatings were analyzed by SEM, EDS, AFM, XRD, microhardness tester and wear tester, respectively. The surface morphologies after wearing were observed and the wear mechanism was discussed. The corrosion behaviors of the coatings before and after heat-treatments were evaluated by anodic polarization in 3.5% sodium chloride solution. The results show that no obvious flaws could be found in the Ni-W alloy coatings and there was a good bond with the matrix. The microhardness of the coatings increased with increasing heat treatment temperature, reaching its maximum value for heat treatment at 500°C, and then droped down. Wear resistance of the coatings was found to be better than that of 16 Mn steel and the heat treatment improved the hardness and wear resistance. The corrosion resistance of the heat-treated coatings increased with increasing the annealing temperature, and best corrosion resistance could be obtained at the temperature of 500°C.


2016 ◽  
Vol 693 ◽  
pp. 605-610
Author(s):  
Y. Shen ◽  
Hong Xiang Wang

In this paper, the coating was prepared by the slurry pack cementation on the surface of Fe-14Mn-6Si-5Ni alloy at 900°C for 10 h. A slurry pack cementation mixture was composed of Cr2O3 used as chrominizing source, pure Al powder as reducer, an activator of NH4Cl and albumen (egg white) as cohesive agent. The microstructure, wear resistance and corrosion resistance of coating has been studied. The results showed that the microstructure of the coating is composed of solid solution with Al and Cr; the microhardness of coating with a value of 460 HV was 1.4 time than that of the matrix alloy, friction coefficient of the coating was 0.35, 1/2 of that of matrix alloy, and the rate of corrosion of coating was lower one order of magnitude than that of the FeMnSi based alloy.


2005 ◽  
Vol 38 (5) ◽  
pp. 787-794 ◽  
Author(s):  
D. Tatchev ◽  
G. Goerigk ◽  
E. Valova ◽  
J. Dille ◽  
R. Kranold ◽  
...  

Primary crystallization of Ni(P) particles in hypoeutectic Ni–P amorphous alloy obtained by electroless deposition has been investigated with ASAXS. The particle size distribution, the size dependence of the particle composition and the amorphous matrix composition were found simultaneously. The size distribution consists of a peak at particle radius of ∼1 nm and a tail spanning from ∼2 to 15 nm. The composition of the particles of the peak changes from ∼14 to ∼2 at.% P as their radius grows from 0.7 to about 3 nm. The particles in the tail of the size distribution (2–15 nm) have nearly constant P content in the range of 0–2 at.%. The matrix composition tends to the eutectic one at the end of the primary crystallization process.


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