In this work, a novel liquid fuel HVOF process fueled with ethanol was used to prepare 75wt%Cr 3 C 2 –25wt%NiCr coatings on AISI304 stainless steel substrate. Taguchi method was employed to optimize the spray parameters (ethanol flow rate, oxygen flow rate, powder feed rate and standoff distance) to achieve better erosion resistance at 90° impact angle. The results indicated that ethanol flow rate and oxygen flow rate were identified as the highly contributing parameters on the erosion wear loss. The important sequence of the spray parameter is ethanol flow rate > oxygen flow rate > standoff distance > powder feed rate. The optimal spray parameter (OSP) for minimum erosion wear loss was obtained under ethanol flow rate of 28slph, oxygen flow rate of 420slpm, powder feed rate of 76.7 g/min and standoff distance of 300mm. The phase composition, microstructure, hardness, porosities, and the erosion wear behaviors of the coatings have been studied in detail. Besides, erosion wear testing of the optimized coating was conducted at 30°, 60° and 90° impact angle using air jet erosion testing machine. The SEM images of the erodent samples were taken to analyze the erosion mechanism.

This study assesses the erosive wear performance of hard-phase-reinforced coatings developed for use on hammer drills employed in mining operations. Several laser-clad coatings consisting of a nickel matrix with various tungsten carbides were evaluated along with two Fe-based alloys, FeCrBSi and FeCrNiBSi, and a WC-CoCr reference layer deposited by HVOF spraying. Erosion tests were conducted in 15° steps up to an angle of 90° and coating performance was determined based on volume loss obtained by 3D profilometry. At low angles, the more brittle materials lost significantly less volume, but at 90°, wear-resistant steel performs almost as well as a hard-phase loaded coating. Laser-clad layers with spherical fused tungsten carbides (FTC) performed better overall than coatings with regular (angular) FTC.

This paper summarizes the results of high-temperature corrosion and erosion tests conducted on a wide range of coating materials, including Cr 3 C 2 -NiCr, Cr 3 C 2 -CoNiCrAlY, TiMoCN-Ni, Stellite 6, NiCrBSi, and Hastelloy C-276. All coatings were deposited on stainless steel substrates by HVOF spraying, and after high-temperature testing, were evaluated by means of SEM and EDX analysis. Of the coating materials evaluated, Hastelloy C-276 provided the best protection against high-temperature corrosion. It also exhibited the highest erosion resistance at a particle impact angle of 90°, but at the sharpest impact angle of 15°, Cr 3 C 2 -NiCr coatings were found to be the most erosion resistant, likely due to the strong bonding of carbide particles in matrix. NiCrBSi coatings, on the other hand, exhibited the highest values of volume loss.

One of the economical and fast solutions for failure against erosive wear in oil and gas industries is the deposition of cermets using HVOF thermal spray. Recently, especially with the new development of bimodal feedstock powders, the composition percentages of the mixed powders have played a key factor in the final coating performance. In the present study, a design of experiment (DOE) software was implemented to study the influence of different powder percentages on the coating performance. The coating mechanical properties and its performance were investigated via dry solid particle erosion tests, hardness measurement and SEM respectively. The results showed that both the hardness and erosion resistance of the coating increases as the composition percentage of the nanostructured WC-12Co increased due to the strong adhesion of WC nano size grains at the substrate/coating interface as a result of improved mechanical interlocking.

HVOF and HVAF deposited coatings of three commercial Fe-based powder alloys have been ranked according to ASTM G76 solid particle erosion testing. The reference was electrolytic hard chrome (EHC) plating. The test results at 30 m/s abrasive particle velocity showed that 6AB powder alloy, when HVAF sprayed, Fe SP586 when both HVOF and HVAF sprayed meet the EHC plating reference erosion rate. 6AB HVOF sprayed and Fe SP529 both HVOF and HVAF sprayed powder alloys achieved two to three times higher erosion rate but were still at the same level of magnitude as the EHC plating reference.

In this present work, WC-Co coatings with different Co contents were deposited by warm spraying using two different powder sizes and their microstructure, hardness, fracture resistance, and wear properties were investigated. The coatings produced from fine powders showed higher hardness and better wear behavior for all Co contents than those deposited from coarse powders, which is attributed to improved splat-splat bonding and a reduction in porosity that comes with using fine powder.

This study examines the high-temperature erosion characteristics of carbide cermet coatings produced by HVOF spraying. The coating materials tested include three Cr 3 C 2 cermets, WC, and WC-Cr 3 C 2 . A low carbon steel and an arc-sprayed iron-base coating are also tested for reference. A nozzle-type elevated-temperature erosion tester is used to spray bed ashes collected from several coal-fired boilers. Coating samples are analyzed and compared based on composition, surface morphology, erosion wastage, and hardness relative to that of the bed-ash particles. From the comparisons, a number of conclusions are drawn. Paper includes a German-language abstract.

This work investigates the particle erosion properties of wear protection layers at high temperatures. The materials tested include tungsten and carbide cermets, nickel alloys, and chromium steel applied by different thermal spraying methods. Among key findings: HVOF-sprayed Cr 3 C 2 -NiCr cermet coatings showed the least amount of wear after particle erosion testing. It was confirmed that erosion resistance depends on elastic-plastic conditions between the particles and coating surface, not layer hardness. The impact of solid particles does not cause abrasion in elastic friction areas and only rarely causes abrasion in regions where plastic plowing occurs. Paper includes a German-language 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.