Microstructure and dry sliding wear behaviour of titania and alumina-titania coatings
TL;DR: The microstructure, hardness and wear properties of atmospheric plasma spray coating of TiO2 and Al2O3-13TiO2 with incremental hydrogen fractions (11·1-23·8%) in primary gas have been investigated in this article.
Abstract: The microstructure, hardness and wear properties of atmospheric plasma spray coating of TiO2 and Al2O3–13TiO2 with incremental hydrogen fractions (11·1–23·8%) in primary gas have been investigated in this work. TiO2 coating shows a fine bead-like surface structure, while Al2O3–13TiO2 predominantly exhibits a splat-like morphology. The microstructure shows a slight refinement in the structure for the highest hydrogen content possibly due to the higher specific enthalpy of the plasma plume. Both coatings show the highest hardness for samples coated with the highest hydrogen content possibly due to the refined structure. The roughness shows a mild decreasing trend for TiO2 coating, while the reverse trend is observed for Al2O3–13TiO2 coating. The wear loss and friction coefficient show a flat trend (0·4–0·6) for all the hydrogen contents. The worn tracks show a compacted mixture of ceramic, graphite and metallic particles.
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TL;DR: In this paper, the authors investigated the effect of Al2O3-40TiO2 (A40T) coating on Inconel 718 alloy and concluded that A40T provides good erosion resistance at elevated temperatures.
Abstract: Nickel based superalloy, Inconel 718, is one of the main candidates for high temperature applications such as air craft, land base and marine turbines. This technical paper deals with high temperature erosion behaviour and its mechanism of Al2O3–40TiO2 (A40T) coating on Inconel 718 alloy. Al2O3–40TiO2 coatings through plasma spray method were made on Inconel 718. The erosion behaviour of the A40T coating was studied using hot air jet erosion experiments at 800°C with varying parameters like angle of impingement and erodent velocity. Characterisation of the samples was carried out using SEM images, and mechanisms of erosion are discussed. Images (SEM) reveal that the A40T coating exhibit ductile and brittle behaviour by ploughing and network cracking with grain chipping at 45° angle of impingement, while at 90°, it is brittle behaviour by network cracking and grain ejection. This investigation concludes that A40T coating on IN718 provides good erosion resistance at elevated temperatures.
17 citations
26 Jul 2019
5 citations
TL;DR: A composite coating on vermicular graphite cast iron reinforced with Al2O3 particulates, processed by selective laser surface alloying, with the thickness of ∼600µm and coverage fraction of 20%, was reported in this article.
Abstract: We report a composite coating on vermicular graphite cast iron reinforced with Al2O3 particulates, processed by selective laser surface alloying, with the thickness of ∼600 µm and coverage fraction of 20%. The original microstructure was thus considerably modified. Different fractions of the Al2O3 particulates were added, ranging from 5 to 25 wt-%. Microhardness and strength were both increased, due to the formation of the composite coating, which led to a series of strengthening mechanisms. In addition, in thermal fatigue test, the crack density was reduced, due to the surface composite coating and the particular scanning strategy. Cracking on the sample surface was effectively restrained by the composite coating.
4 citations
Additional excerpts
...‘worm-like’ graphite in its microstructure [1]....
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TL;DR: In this paper, the influence of nano-Cu and Ni nanoparticle suspensions (2 wt-%) in commercially available engine oil (15W40) has been investigated on friction and wear behavior of Al2O3-13TiO2 coatings.
Abstract: The influence of Cu and Ni nanoparticle suspensions (2 wt-%) in commercially available engine oil (15W40) has been investigated on friction and wear behaviour of Al2O3–13TiO2 coatings. Lab synthesised nano-Cu and Ni suspensions have been compared with one commercially available nano-Cu suspension. Results show that lab synthesised Cu and Ni increases the oil viscosity by 12 and 20% for Ni and Cu respectively. However, the commercially available nano-Cu has reduced the viscosity by 8%. Lab synthesised Cu and Ni showed slightly reduced friction coefficient with significantly higher mass loss compared to virgin base oil and commercially available nano-Cu. The abrasive nature of these particles may possibly predominate in higher viscosity medium generating steady wear particles from the softer counterpart. Commercially available nano-Cu shows higher and irregular friction profile with mass loss equal to base oil possibly due to reduced viscosity.
3 citations
TL;DR: Alumina-titania thick coatings with finely layered microstructure are usually deposited using Air Plasma Spraying (APS) process as mentioned in this paper, nitrogen or argon is used as the primary plasma...
Abstract: Alumina-titania thick coatings with finely layered microstructure are usually deposited using Air Plasma Spraying (APS) process. In the APS process, nitrogen or argon is used as the primary plasma ...
2 citations
References
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01 Jan 2012
139,059 citations
"Microstructure and dry sliding wear..." refers background in this paper
...Partially melted zones in this nanostructured coating, which strengthen the matrix, are claimed to be responsible for its superior wear resistance.(11,12) The quality, morphology and volume fraction of the feed powder along with the various spray parameters predominantly influence the final coating properties....
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TL;DR: In this paper, the authors investigated the response of titanium to oxidation at various temperatures and timings, in terms of layer thickness, phase evolution, surface morphology, oxide layer-substrate adhesion, hardness and tribological characteristics.
173 citations
TL;DR: In this paper, the tribological behavior of self-mated ceramic composites, like SiC, TiC, Si 3 N 4 TiN and (Ti,Mo)(C,N) + Ni, were characterized under dry sliding friction.
165 citations
TL;DR: In this paper, the microstructure, mechanical properties and abrasion wear resistance of alumina/titania ceramic coatings deposited with nano- and micro-structured powders by high-velocity oxygen fuel (HVOF) and plasma spray (PS) processes were evaluated.
Abstract: We have evaluated the microstructure, mechanical properties and abrasion wear resistance of alumina/titania ceramic coatings deposited with nano- and micro-structured powders by high-velocity oxygen fuel (HVOF) and plasma spray (PS) processes. The deposition guns have a strong influence on the mechanical properties and abrasive wear resistance of the coatings, but the powders do not. The coatings deposited by HVOF are significantly harder and tougher, and their abrasion resistance is two–three-fold higher. Plastic microcutting plays the predominant role in abrasion wear of the coating deposited by HVOF. A combination of brittleness and porosity results in fracture that dominates the abrasion wear of plasma-sprayed coatings. The abrasion resistance measured follows an Evans–Marshall equation modified to account for the effects of porosity.
136 citations
TL;DR: In this paper, the effects of TiO 2 addition on the properties of the coating were investigated in terms of microhardness and fracture toughness values, and the results indicated that an increase in TiO2 amount improves fracture toughness and lowers the micro-hardness values of the coatings.
Abstract: Plasma sprayed ceramic coatings are successfully used in many industrial applications, where high wear and corrosion resistance with thermal insulation are required. In this study, various types of Al 2 O 3 –TiO 2 plasma sprayed coatings in different compositions (Al 2 O 3 –13 wt.% TiO 2 , Al 2 O 3 –40 wt.% TiO 2 and Al 2 O 3 –50 wt.% TiO 2 ) were prepared on an AISI 304L austenitic stainless steel substrate. The effects of TiO 2 addition on the properties of the coating were investigated in terms of microhardness and fracture toughness values. The results obtained from experimental work were evaluated with standard characterisation techniques. The results indicated that an increase in TiO 2 amount improves fracture toughness and lowers the microhardness values of the coatings.
128 citations