Formation of Structure of HVOF Sprayed WC-Co Coating on a Copper Substrate

1997 ◽  
Author(s):  
V.V. Sobolev ◽  
J.M. Guilemany ◽  
J.A. Calero
Keyword(s):  
Crystalline Structure ◽  
Substrate Surface ◽  
Copper Substrate ◽  
Interfacial Region ◽  
Solidification Velocity ◽  
Spray Parameters ◽  
Hvof Spraying ◽  
Mechanisms Of Development ◽  
Oxygen Fuel ◽  
Cooling Velocity

Abstract Mathematical modelling of the formation of the WC-Co coating structure and adhesion on copper substrate during high velocity oxygen-fuel (HVOF) spraying is provided. Smooth (polished) and rough (grit blasted) substrates are considered. Variations of solidification time, solidification velocity, thermal gradient, and cooling velocity in the coating and substrate interfacial region are studied. Formation of the amorphous and crystalline structures in the coating and of the crystalline structure in the substrate interfacial region is investigated. Behaviour of the crystal size and intercrystalline distance with respect to the thermal spray parameters and morphology of the substrate surface is analysed. Optimal conditions for the development of fine and dense crystalline structure are determined. Mechanical and thermal mechanisms of development of the substrate-coating adhesion are discussed. Results obtained agree well with experimental data.

Failure Analysis of the outside Coating on the Furnace Roller

2016 ◽  
Vol 853 ◽  
pp. 431-435 ◽  
Author(s):  
Zheng Qu Feng ◽  
Lu Wang ◽  
Wei Ze Wang ◽  
Kai Di Cheng ◽  
Cheng Zhou Chen
Keyword(s):  
Failure Analysis ◽  
Substrate Surface ◽  
Low Carbon Steel ◽  
Substrate Material ◽  
Composition Analysis ◽  
Low Carbon ◽  
Hvof Spraying ◽  
Microstructure Observation ◽  
Oxygen Fuel ◽  
Peeling Off

A failure case of the outside coating on the furnace roller is presented in this study. The coating consists of WC-Co, which is deposited on 45 steel by High Velocity Oxygen Fuel (HVOF) spraying. The spalling of coatings has been found in the middle of the roller. Rust was also observed on the coatings of the roller. The failure analysis of the coating was performed in terms of composition analysis, and microstructure observation etc. In addition, the effects of different sandblasting post-treatments were compared. And the effect of substrate material is investigated on the corrosion of coatings. It was concluded that the sandblasting particles remained on the substrate surface have effects on the failure of the coating. The peeling-off coating on the roller is also related with the formation of iron oxides. Less sand can be remained on the substrate surface when air purging and brushing is used after the sand-blasting compared with air purging or non-treatment is applied. The stainless steel shows more excellent corrosion resistance than the low carbon steel when they are used as substrate for WC-Co coatings.

Application of Taguchi Method and Anova Techniques to Maximize HVOF Spraying to WC-12Co

2020 ◽  
Vol 854 ◽  
pp. 109-116
Author(s):  
Văn Chien Dinh ◽  
Tuan Hai Nguyen ◽  
Khac Linh Nguyen
Keyword(s):  
Taguchi Method ◽  
Optimization Problem ◽  
Steel Substrate ◽  
Experimental Result ◽  
Spray Parameters ◽  
Anova Analysis ◽  
Spray Distance ◽  
Hvof Spraying ◽  
Oxygen Fuel ◽  
16Mn Steel

The purpose of this study was to achieve a low-porosity HVOF (High velocity Oxygen Fuel) spray cover and to determine the effect of spray parameters on the porosity of the coating. The spray parameters studied include: Powder feed rate (A); Spray distance (B); Oxygen/Propane ratio to porosity of WC-12Co coating on 16Mn steel. Taguchi method and ANOVA (Analysis of variance) technique were used to optimize and analyze the effect of spray parameters. The results showed that the optimum spray parameters with A = 26 g/min, B = 0.2m, C = 5 for porosity smallest. Factor A has the greatest influence on porosity, followed by B and C. The experimental result is then compared to optimal results and the error is only 4.2 %. Hence, one can say that the optimal results are reliable and Taguchi method - ANOVA technique proved to be an effective solution to the optimization problem. Parameters for a WC-12Co coating with improved porosity on 16Mn steel substrate have been identified.

In vitro Behaviour of Alumina-Hydroxiapatite Composites Coatings

2018 ◽  
Vol 69 (6) ◽  
pp. 1416-1418
Author(s):  
Alexandru Szabo ◽  
Ilare Bordeasu ◽  
Ion Dragos Utu ◽  
Ion Mitelea
Keyword(s):  
Pure Titanium ◽  
Titanium Substrate ◽  
High Strength ◽  
Biological Properties ◽  
Commercially Pure Titanium ◽  
Hvof Spraying ◽  
Before And After ◽  
Sbf Solution ◽  
Oxygen Fuel

Hydroxyapatite (HA) is a very common material used for biomedical applications. Usually, in order to improve its poor mechanical properties is combined or coated with other high-strength materials.The present paper reports the manufacturing and the biocompatibility behaviour of two different biocomposite coatings consisting of alumina (Al2O3) and hydroxyapatite (HA) using the high velocity oxygen fuel (HVOF) spraying method which were deposited onto the surface of a commercially pure titanium substrate. The biological properties of the Al2O3-HA materials were evaluated by in vitro studies. The morphology of the coatings before and after their immersing in the simulated body fluid (SBF) solution was characterized by scanning electron microscopy (SEM). The results showed an important germination of the biologic hydroxyapatite crystallite on the surface of both coatings.

Development and Application of Repairing and Protection Technologies for Desulfurization Pump

2012 ◽  
Vol 538-541 ◽  
pp. 290-297
Author(s):  
Tai Jiang Li ◽  
Wei Li ◽  
Yong Li ◽  
Fu Guang Liu ◽  
Li Ying Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Arc Welding ◽  
Protective Coatings ◽  
Hvof Spraying ◽  
Cermet Coating ◽  
Field Service ◽  
Gas Tungsten Arc ◽  
Metal Arc Welding ◽  
Protection Technology ◽  
Oxygen Fuel

Gypsum and slurry with high content of Cl- lead to the damage of desulfurization pump caused by erosion and corrosion. Gas tungsten arc welding (GTAW) and shield metal arc welding (SMAW) were employed to develop weld repairing technology. High-velocity oxygen fuel (HVOF) spraying was employed to prepare NiCr cermet coating and WC cermet coating against erosion and corrosion. Microstructures and mechanical properties of the weld and the protective coatings were tested. The mechanical properties of the weld joints with duplex microstructure were in accordance with related standards. The technology of HVOF sprayed NiCr cermet coating was selected to prolong the service lifetime and was applied on the pump casing and impeller repaired by using the weld repairing procedures developed in this study. The integrity of the pump parts after 30 months in-field service confirmed the reliability of the repairing technology and the protection technology.

Properties of TiC-Ni Based Coatings Deposited by Different HVOF Spraying

2000 ◽  
Author(s):  
P. Vuoristo ◽  
M. Väisänen ◽  
T. Mäntylä ◽  
L.-M. Berger
Keyword(s):  
Wear Resistance ◽  
Flame Temperature ◽  
Oxygen Flow ◽  
Spray Parameters ◽  
Coating Properties ◽  
Hvof Spraying ◽  
Fuel Gas ◽  
Wear Rates ◽  
Operation Conditions ◽  
Satisfactory Coating

Abstract Hardmetal-like coatings of the TiC-Ni system are potential for use as wear, corrosion and heat resistant coatings in various operation conditions. Our previous works [1-12] have shown that these materials are well sprayable using different thermal spray processes such as plasma, D-Gun and HVOF spraying. Since HVOF spraying is today the most important process used to apply carbide based coatings, this study was carried out in order to evaluate more systematically the sprayability of these novel spray powders and the influence of HVOF spray parameters on some coating properties. Coating samples were prepared by using DJ Hybrid gun with propane as a fuel gas, and a CDS gun with hydrogen fuel gas. Oxygen flow rate was varied in both cases for changing the flame temperature. Microstructure, phase composition, hardness, and abrasion wear resistance of the coated samples were investigated. The results showed that both HVOF processes used give satisfactory coating properties and that the use of high oxygen flow rates is beneficial for improving the wear resistance of the coatings. Powders with fine particle size are beneficial in the DJ Hybrid process; the use of coarse powders results in coatings with somewhat higher wear rates. The optimum spray condition for the TiC-Ni system powders differs from that typically used for conventional WC-Co and Cr3C2-NiCr powders by a higher flame temperature.

High Temperature Erosion Properties of Thermal Barrier Coatings Produced by Acetylene Sprayed High Velocity Oxygen Fuel Process

2000 ◽  
Author(s):  
M.A. Cole ◽  
R. Walker
Keyword(s):  
High Temperature ◽  
Thermal Barrier Coatings ◽  
High Velocity ◽  
Thermal Barrier ◽  
High Velocity Oxygen Fuel ◽  
Hvof Spraying ◽  
Powder Morphology ◽  
Fuel Gas ◽  
Barrier Coatings ◽  
Oxygen Fuel

Abstract Over the past 30 years, there has been considerable interest in the development of thermally sprayed thermal barrier coatings (TBCs) for aerospace and land based turbine applications. The use of TBCs enables higher operating temperatures, resulting in significant fuel efficiency savings. This paper reports on the development of dense Yttria Stabilised Zirconia (YSZ) thermal barrier coatings produced by High Velocity Oxygen Fuel (HVOF) spraying using acetylene as the fuel gas. The use of a high temperature gas erosion rig allowed the controlled evaluation of erodent size, velocity, impact angle, and temperature on coating performance. The work also covers the optimization of process parameters, including powder morphology, stand-off distance, oxygen to fuel ratio, gas pressures, and flowrates, and their effect on coating characteristics such as deposition efficiency, microhardness, and surface roughness.

scholarly journals Effects of Temperature on Wear Properties and Mechanisms of HVOF Sprayed CoCrAlYTa-10%Al2O3 Coatings and H13 Steel

Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1224
Author(s):  
Zheng Wei ◽  
Yuping Wu ◽  
Sheng Hong ◽  
Weihua Yang ◽  
Wei Shi
Keyword(s):  
Wear Rate ◽  
Wear Properties ◽  
H13 Steel ◽  
Hvof Spraying ◽  
Different Temperatures ◽  
Effects Of Temperature ◽  
Increasing Temperature ◽  
Worn Surface ◽  
Oxygen Fuel ◽  
Better Than

In this study, the CoCrAlYTa-10%Al2O3 coatings were prepared by the high-velocity oxygen-fuel (HVOF) spraying. A series of ball-on-disk sliding wear tests were conducted to evaluate the tribological properties of the coatings at different temperatures (25 °C, 200 °C, 400 °C, and 600 °C). The results showed that the average coefficients of friction (COFs) of the CoCrAlYTa-10%Al2O3 coatings were lower than that of H13 steel at different temperatures. The average COFs of the CoCrAlYTa-10%Al2O3 coatings and H13 steel both decreased with increasing temperature. The wear rate of the CoCrAlYTa-10%Al2O3 coatings increased first and then decreased. The microhardness of worn surface of the CoCrAlYTa-10%Al2O3 coatings increased with increasing temperature, while the microhardness of worn surface of H13 steel at 25 °C and 200°C was higher than that at 400 °C and 600 °C. The wear mechanism of the two materials was mainly abrasive wear. The tribofilms were formed on the worn surface of the CoCrAlYTa-10%Al2O3 coatings, which had a good protective effect. Due to thermal softening and low binding strength of debris, it was difficult for H13 steel to form the tribofilms. The wear rate of H13 steel was much higher than that of the CoCrAlYTa-10%Al2O3 coatings at 400 °C and 600 °C, indicating that the high temperature wear resistance of the coatings was much better than that of H13 steel.

Effect of Copper Substrate Surface Orientation on the Reductive Functionalization of Graphene

2019 ◽  
Vol 31 (21) ◽  
pp. 8639-8648
Author(s):  
Xu Zhang ◽  
Da Luo ◽  
Hanyang Zhang ◽  
Dae Yeon Hwang ◽  
Sung O. Park ◽  
...  
Keyword(s):  
Substrate Surface ◽  
Copper Substrate ◽  
Surface Orientation ◽  
Effect Of Copper
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