Abrasion-Corrosion of Thermal Spray Coatings

WC-based thermal-spray and High Velocity Oxy-Fuel (HVOF) coatings are extensively used in a wide range of applications ranging from downhole drilling tools to gas turbine engines. WC-based thermal spray coatings offer improved wear resistance as a result of hard phases dispersed in binder-rich regions. However, the presence of hard and soft phases within the coating can also lead to the formation of micro-galvanic couplings in aqueous environments leading to some reduction in combined wear-corrosion resistance. Furthermore, the coating also responds differently to change in mechanical loading conditions. This chapter examines the wear-corrosion performance of thermal spray coatings in a range of wear, electrochemical, and wear-corrosion tests under varying contact conditions to develop models and establish relationships between wear mechanisms, wear rates, and environmental factors such as pH and applied load.

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Sliding Wear of Conventional and Suspension Sprayed Nanocomposite WC-Co Coatings: An Invited Review

Journal of Thermal Spray Technology ◽

10.1007/s11666-021-01185-z ◽

2021 ◽

Author(s):

R. Ahmed ◽

O. Ali ◽

C. C. Berndt ◽

A. Fardan

Keyword(s):

Wear Rate ◽

Thermal Spray ◽

Sliding Wear ◽

Failure Modes ◽

Thermal Spray Coatings ◽

Annual Growth Rate ◽

Total Energy Consumption ◽

Wear Performance ◽

Wear Rates ◽

Spray Coatings

AbstractThe global thermal spray coatings market was valued at USD 10.1 billion in 2019 and is expected to grow at a compound annual growth rate of 3.9% from 2020 to 2027. Carbide coatings form an essential segment of this market and provide cost-effective and environmental friendly tribological solutions for applications in aerospace, industrial gas turbine, automotive, printing, oil and gas, steel, and pulp and paper industries. Almost 23% of the world’s total energy consumption originates from tribological contacts. Thermal spray WC-Co coatings provide excellent wear resistance for industrial applications in sliding and rolling contacts. Some of these applications in abrasive, sliding and erosive conditions include sink rolls in zinc pots, conveyor screws, pump housings, impeller shafts, aircraft flap tracks, cam followers and expansion joints. These coatings are considered as a replacement of the hazardous chrome plating for tribological applications. The microstructure of thermal spray coatings is however complex, and the wear mechanisms and wear rates vary significantly when compared to cemented WC-Co carbides or vapour deposition WC coatings. This paper provides an expert review of the tribological considerations that dictate the sliding wear performance of thermal spray WC-Co coatings. Structure–property relationships and failure modes are discussed to grasp the design aspects of WC-Co coatings for tribological applications. Recent developments of suspension sprayed nanocomposite coatings are compared with conventional coatings in terms of performance and failure mechanisms. The dependency of coating microstructure, binder material, carbide size, fracture toughness, post-treatment and hardness on sliding wear performance and test methodology is discussed. Semiempirical mathematical models of wear rate related to the influence of tribological test conditions and coating characteristics are analysed for sliding contacts. Finally, advances for numerical modelling of sliding wear rate are discussed.

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An Analysis of Environmental Factors Affecting Corrosion Behaviour of Thermal Spray Cermet Coatings

Thermal Spray 1998: Proceedings from the International Thermal Spray Conference ◽

10.31399/asm.cp.itsc1998p0063 ◽

1998 ◽

Author(s):

T. Hodgkiess ◽

A. Neville

Keyword(s):

Thermal Spray ◽

Corrosion Behaviour ◽

Strong Dependence ◽

Thermal Spray Coatings ◽

Microscopical Examination ◽

Material Loss ◽

Factors Affecting ◽

Spray Coatings ◽

Aqueous Environments ◽

Coating Durability

Abstract Primarily thermal-spray coatings have been developed to combat excessive degradation of components due to mechanical wear. However, these coatings are increasingly being required to function in aqueous environments where corrosive attack is possible. The durability of thermal spray coatings in terms of corrosion resistance is the focus of this paper. Two types of coatings have been studied ; High-Velocity Oxy-Fuel (HVOF) and thermal spray-fused. 'the HVOF coating was WC-Co-Cr and the spray-fused coatings were WC-Co based and Ni-Cr-Si-B. Samples have been exposed to aqueous environments at a range of different temperatures and of varying salinity (500ppm and 35,000ppm Total Dissolved Solids) in order to simulate freshwater and seawater environments. The detailed material loss and degradation mechanisms have been investigated using electrochemical-monitoring techniques supported by precise post-test microscopical examination using light microscopy, scanning electron and atomic force microscopy and x-ray microanalysis. The study has demonstrated that there is a strong dependence on coating durability for all the coatings as a function of temperature but salinity has a lesser effect. However there are interesting differences in the extent and detailed mechanisms of such effects between the different coatings.

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Thermal Spray Coatings for Corrosion Protection in Atmospheric and Aqueous Environments

Corrosion: Materials ◽

10.31399/asm.hb.v13b.a0003832 ◽

2005 ◽

pp. 422-429

Keyword(s):

Corrosion Protection ◽

Thermal Spray ◽

Thermal Spray Coatings ◽

Spray Coatings ◽

Aqueous Environments

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USE OF IBA TECHNIQUES TO CHARACTERIZE HIGH VELOCITY THERMAL SPRAY COATINGS

Modern Physics Letters B ◽

10.1142/s0217984901003354 ◽

2001 ◽

Vol 15 (28n29) ◽

pp. 1428-1436 ◽

Cited By ~ 2

Author(s):

W. TROMPETTER ◽

A. MARKWITZ ◽

M. HYLAND

Keyword(s):

Thermal Spray ◽

High Velocity ◽

Sliding Wear ◽

Thermal Spraying ◽

Thermal Spray Coatings ◽

Spray Coatings ◽

The Past ◽

Composition And Structure ◽

Wide Range ◽

Sprayed Coating

Spray coatings are being used in an increasingly wide range of industries to improve the abrasive, erosive and sliding wear of machine components. Over the past decade industries have moved to the application of supersonic high velocity thermal spray techniques. These coating techniques produce superior coating quality in comparison to other traditional techniques such as plasma spraying. To date the knowledge of the bonding processes and the structure of the particles within thermal spray coatings is very subjective. The aim of this research is to improve our understanding of these materials through the use of IBA techniques in conjunction with other materials analysis techniques. Samples were prepared by spraying a widely used commercial NiCr powder onto substrates using a HVAF (high velocity air fuel) thermal spraying technique. Detailed analysis of the composition and structure of the power particles revealed two distinct types of particles. The majority was NiCr particles with a significant minority of particles composing of SiO 2/ CrO 3. When the particles were investigated both as raw powder and in the sprayed coating, it was surprising to find that the composition of the coating meterial remained unchanged during the coating process despite the high velocity application.

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METAL-MATRIX COMPOSITES AND THERMAL SPRAY COATINGS FOR EARTH MOVING MACHINES

10.2172/816484 ◽

2003 ◽

Author(s):

D. Trent Weaver ◽

Matthew T. Kiser ◽

Jeffrey Hawk

Keyword(s):

Metal Matrix Composites ◽

Thermal Spray ◽

Metal Matrix ◽

Thermal Spray Coatings ◽

Matrix Composites ◽

Spray Coatings

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Design, Development and Application of Vehicle Gas Turbine Engines

Proceedings of the Institution of Mechanical Engineers Automobile Division ◽

10.1243/pime_auto_1966_181_021_02 ◽

1966 ◽

Vol 181 (1) ◽

pp. 149-172

Author(s):

P. A. Phillips ◽

Peter Spear

Keyword(s):

Gas Turbine ◽

Gas Turbines ◽

Low Cost ◽

Engine Performance ◽

Turbine Engines ◽

Gas Turbine Engines ◽

Design Development ◽

Turbine Engine ◽

Wide Range ◽

Cycle Temperature

After briefly summarizing worldwide automotive gas turbine activity, the paper analyses the power plant requirements of a wide range of vehicle applications in order to formulate the design criteria for acceptable vehicle gas turbines. Ample data are available on the thermodynamic merits of various gas turbine cycles; however, the low cost of its piston engine competitor tends to eliminate all but the simplest cycles from vehicle gas turbine considerations. In order to improve the part load fuel economy, some complexity is inevitable, but this is limited to the addition of a glass ceramic regenerator in the 150 b.h.p. engine which is described in some detail. The alternative further complications necessary to achieve satisfactory vehicle response at various power/weight ratios are examined. Further improvement in engine performance will come by increasing the maximum cycle temperature. This can be achieved at lower cost by the extension of the use of ceramics. The paper is intended to stimulate the design application of the gas turbine engine.

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The Effects of Ambient Conditions on Gas Turbine Emissions—Generalized Correction Factors

Journal of Engineering for Power ◽

10.1115/1.3446412 ◽

1978 ◽

Vol 100 (4) ◽

pp. 640-646 ◽

Cited By ~ 2

Author(s):

P. Donovan ◽

T. Cackette

Keyword(s):

Gas Turbine ◽

Pressure Ratio ◽

Turbine Engines ◽

Inlet Temperature ◽

Gas Turbine Engines ◽

Correction Factors ◽

Oxides Of Nitrogen ◽

Ambient Conditions ◽

Nitrogen Emission ◽

Wide Range

A set of factors which reduces the variability due to ambient conditions of the hydrocarbon, carbon monoxide, and oxides of nitrogen emission indices has been developed. These factors can be used to correct an emission index to reference day ambient conditions. The correction factors, which vary with engine rated pressure ratio for NOx and idle pressure ratio for HC and CO, can be applied to a wide range of current technology gas turbine engines. The factors are a function of only the combustor inlet temperature and ambient humidity.

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