Abrasive wear behaviour of conventional and nanocomposite HVOF-sprayed WC–Co coatings

Warm spray (WS) is a modification of high-velocity oxy-fuel spraying, in which the temperature of the supersonic gas flow generated by the combustion of kerosene and oxygen is controlled by diluting the combustion flame with an inert gas such as nitrogen. The inert gas is injected into the mixing chamber placed between the combustion chamber and the powder feed ports, thus the temperature of the propellant gas can be controlled from~700 to 2,000 K. Since WS allows for higher particle temperatures in comparison to cold spray, warm sprayed particles are more softened upon impact, thus resulting in greater deformation facilitating the formation of shear instability for bonding. Recently, the combustion pressure of WS has been increased from 1 (low-pressure warm spray) to 4 MPa (high-pressure warm spray) in order to increase the velocity of sprayed particles. Effects of spray parameters on microstructure, mechanical properties, and splats formation of Ti-6Al-4V were systematically studied. Obtained coatings were examined by analyzing the coating cross-section images, microhardness as well as oxygen content. In addition, flattening ratio of splats was calculated as a function of nitrogen flow rate. It was found that the increased particle velocity caused by the increased combustion pressure had significant beneficial effects in terms of improving density and controlling the oxygen level in the sprayed Ti-6Al-4V coatings.

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“…[1][2][3][4][5][6][7][8][9][10]. The mixture ratio of kerosene to oxygen was fixed at the stoichiometric ratio for complete combustion.…”

Section: Warm Spray Conditionsmentioning

confidence: 99%

Warm Spray Forming of Ti-6Al-4V

et al. 2013

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“…WCCo ball is a famous abrading counterface for the tribological applications [18]. In general, WCCo is used for the abrasive applications and machining process of the metals in industry.…”

Section: Resultsmentioning

confidence: 99%

Wear Properties of the Surface Alloyed AISI 1020 Steel with Vanadium and Boron by TIG Welding Technique

Abakay¹,

Şen²,

Şen³

2014

Acta Phys. Pol. A

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It is now well known that surface alloying caused improvement in the mechanical/chemical properties of near surface regions of materials. In the present study, surface alloying treatment with boron, vanadium and iron on the AISI 1020 steel was realized by the technique of TIG welding. Ferrous boron, ferrous vanadium and Armco iron were used for surface alloying treatment. Before the treatment, ferrous alloys were ground and sieved to be smaller than 38 µm. The powders were mixed to be composed of Fe15−xVxB5, where x = 1, 3, and 5 (by at.). Prepared powders were pressed on the steel substrate and melted by TIG welding for surface alloying. Coated layers formed on the steel substrate were investigated using scanning electron microscopy, X-ray diraction analysis and Vickers microhardness testers. It was shown that the surface alloyed layer has a composite structure including steel matrix and eutectic borides. Wear tests of the surface alloyed AISI 1020 steels were realized against WCCo ball using ball-on-disk method.

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“…However, large-scale cracking of the coating as a result of high-temperature heat treatments, can result in localized preferential wear within the coating (as can be seen in Fig. 5) [7]. However, Shipway et al have explained, it was possible that surface material loss can be caused predominantly by pullout of tungsten carbide particles and also by subsurface cracking (caused by the presence of the highly decomposed regions within the microstructure) and therefore, higher wear rates can be expected for specimens heat treated in the air [20].…”

Section: Analysis Of Wear Tracksmentioning

confidence: 99%

“…Stewart et al reported a decreased wear resistance of HVOF cermet coatings as a result of decomposition of WC and the formation of additional W 2 C and soft metallic tungsten [7]. It also has been argued that formation of a brittle η amorphous phase between W, C and other binding metals (i. e. cobalt) as a result of heat treatment can affect the hardness and wear resistance of the coatings.…”

Section: Introductionmentioning

confidence: 99%

Effect of Heat Treatment on Wear Performance of Nanostructured WC-Ni/Cr HVOF Sprayed Coatings

2017

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The extraction and processing of bitumen from oil sands exposes machinery parts to constant abrasive wear which can cause severe surface degradation and component failure, resulting in production shut-downs. To reduce the effect of wear on performance of production machinery, wear resistant coatings must be used to extend component life. Recently, thick microstructured cermet coatings based on WC dispersions have been used to protect surfaces. In this study a nanostructured 83WC-17Ni/Cr coating was deposited on to C-Mn steel surfaces using High Velocity Oxy-Fuel (HVOF) spraying. The effect of heat treatment in air and nitrogen atmosphere on changes in the microstructure, hardness and wear resistance was investigated. The results showed that both the hardness and wear resistance increased with increasing heat treatment temperature in both air and nitrogen atmosphere. However, the use of heat treatments in air led to the formation of brittle metal oxides which resulted in micro-cracking within the coatings. This caused the coatings to fail by brittle fracture during wear testing. In comparison heat treatment in nitrogen produced better wear resistance because metal oxide formation was avoided.

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Abrasive wear behaviour of conventional and nanocomposite HVOF-sprayed WC–Co coatings

Cited by 354 publications

References 23 publications

Warm Spray Forming of Ti-6Al-4V

Warm Spray Forming of Ti-6Al-4V

Wear Properties of the Surface Alloyed AISI 1020 Steel with Vanadium and Boron by TIG Welding Technique

Effect of Heat Treatment on Wear Performance of Nanostructured WC-Ni/Cr HVOF Sprayed Coatings

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