Methods of Determination and Control of Residual Stresses in Plasma Spray Coatings

1997 ◽  
Author(s):  
L. Dekhtyar ◽  
A. Kleyman ◽  
V. Andreychuk ◽  
S. Berman
Keyword(s):  
Residual Stresses ◽  
Thermal Spray ◽  
Plasma Spray ◽  
Thermal Spraying ◽  
Thermal Spray Coatings ◽  
Coating Deposition ◽  
Spray Coatings ◽  
Plasma Spray Coatings ◽  
And Control ◽  
Elastic Characteristics

Abstract Residual stresses exert profound influence on the longevity of parts with thermal spray coatings. The distribution and value of the residual stresses depend on method of coating deposition, composition of the applied material, parameters of thermal spraying and methods of post-treatment. Therefore, the study of the influence of the various technological factors on the residual stresses in the plasma spray coatings is very important. Due to heterogeneity of the coating, residual stresses can be determined only by the experimentation by using new methods which take into consideration real values of elastic characteristics and density of elementary layers. Methods and formulas for the calculations of the residual stresses in coatings deposited on bars, rings, discs, cylinders are presented. Experimental results for the various thermal spray coatings are also shown. These results can be used for the optimization of coating deposition and would supplement the existing database.

Comprehensive Methods for Studying Microinhomogeneity in Thermal Spray Coatings with Amorphous-Crystalline Structure

1998 ◽  
Author(s):  
G. Grigorenko ◽  
A. Borisova
Keyword(s):  
Thermal Spray ◽  
Crystalline Structure ◽  
Structural Phase ◽  
Thermal Spraying ◽  
Integrated Approach ◽  
Thermal Spray Coatings ◽  
Chemical Heterogeneity ◽  
New Approach ◽  
X Ray ◽  
Spray Coatings

Abstract An integrated approach was developed for investigation of thermal spray coatings with the amorphous-crystalline structure. The new approach combines methods of metallography, differential thermal and X-ray phase analysis, scanning electron microscopy and X-ray microanalysis. This makes it possible to reveal structural, phase and chemical heterogeneity, determine the degree of amorphization of coatings, temperature and heat of crystallization of the amorphous phase during heating. The new integrated approach was used to study amorphous-crystalline coatings of the Ni-P, Fe-Ni-B and Fe-B systems produced by thermal spraying.

Image-Based Modeling for Assessing Thermal Conductivity of Thermal Spray Coatings at Ambient and High Temperature

2006 ◽  
Author(s):  
Y. Tan ◽  
A. Sharma ◽  
J. P. Longtin ◽  
S. Sampath ◽  
H. Wang
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Thermal Spray ◽  
Process Parameters ◽  
Thermal Spraying ◽  
Thermal Spray Coatings ◽  
Analysis Model ◽  
Element Analysis ◽  
Spray Coatings ◽  
Coating Microstructure

Thermal spray coatings are used extensively for protection of engineering components and structures in a variety of applications. Due to the nature of thermal spraying process, the coating thermal, mechanical, and electrical properties depend strongly on the coating microstructure, which consists of many individual splats, interfaces between the splats, defects and voids. The coating microstructure, in turn, is determined by the thermal spray process parameters. In order to relate coating process parameters to the final coating performance, then, it is desirable to relate coating microstructure to coating properties. In this work, thermal conductivity is used as the physical parameter of interest. Thermal conductivity of thermal spray coatings is studied by using an image analysis-based approach of typical coating cross sections. Three coating systems, yttria stabilized zirconia (YSZ), molybdenum, and Ni-5wt.%Al are explored in this work. For each material, thermal conductivity is simulated by using a microstructure image-based finite element analysis model. The model is then applied to high temperature conditions (up to 1200 °C) with a hot stage-equipped scanning electron microscope imaging technique to assess thermal conductivity at high temperatures. The coating thermal conductivity of metallic coatings is also experimentally measured by using a high-temperature laser flash technique.

scholarly journals Optimization and Process Control for High Performance Thermal Spray Coatings

2000 ◽  
Author(s):  
Christian Moreau ◽  
Luc Leblanc
Keyword(s):  
Process Control ◽  
Thermal Spray ◽  
Plasma Spray ◽  
High Performance ◽  
Thermal Spray Coatings ◽  
Wear Resistant Coatings ◽  
Spray Coatings ◽  
Consistent Manner ◽  
The Stability ◽  
Sprayed Coatings

Abstract Thermal spray coatings are used to protect surfaces against exposure to severe conditions. To insure a reliable protection, not only the structure and properties of the sprayed coatings must be optimized but also one needs to develop appropriate process control techniques to produce high performance coatings in a consistent manner, day after day. This is particularly important during plasma spraying as the wear of the electrodes affects significantly the plasma characteristics and consequently the coating properties. First, in this paper, the stability of plasma spray processes is investigated by monitoring in-flight particle characteristics and plasma fluctuations. Secondly, the possibility and advantages of controlling plasma spray processes by monitoring and regulating the condition of the sprayed particles are discussed. Finally, we will see how the properties of thermal barrier coatings and wear resistant coatings can be optimized by controlling the temperature and velocity of the sprayed particles both in the plasma spray and HVOF (high velocity oxy-fuel) processes.

Elasticity Characteristics of Plasma Spray Coatings

1996 ◽  
Author(s):  
L. Dekhtyar ◽  
A. Kleyman ◽  
S. Berman ◽  
V. Andreychuk
Keyword(s):  
Residual Stresses ◽  
Thermal Spray ◽  
Coating Thickness ◽  
Quantitative Methods ◽  
Spray Coating ◽  
Thermal Spray Coating ◽  
Spray Parameters ◽  
Spray Coatings ◽  
Real Value ◽  
Elastic Characteristics

Abstract Future development of thermal spray processes and new composite materials raises an important problem concerning the transition from qualitative to quantitative methods of coatings evaluation. It is well known that thermal spray coating deposition in most cases is accompanied by the formation of temporal and residual stresses through the coating thickness. For proper evaluation of formed stressed state it is extremely important to know the real value of elastic characteristics in different layers of the coating. This problem has become more complicated taking into consideration the variety of materials, different spray parameters, number of coating layers and extreme service conditions. These values can be obtained only from experimentation. Elastic characteristics (EC) could be used in many calculations, such as durability, stiffness, fatigue, vibration and others. This paper describes new methods of experimental determination of elastic characteristics presumed as variable throughout the coating thickness. Influence of coating composition, particle size of initial powders, spray parameters, post-treatment and other factors on elastic modulusses were studied. Obtained experimental data for different materials supplement existing data and can be used for evaluation of residual stresses and other purposes.

Development of Plasma Spray Coatings Using Linz-Donawitz (LD) Slag Particles

2015 ◽  
Author(s):  
Pravat Ranjan Pati ◽  
Alok Satapathy
Keyword(s):  
Adhesion Strength ◽  
Plasma Spray ◽  
Value Added ◽  
Deposition Efficiency ◽  
Low Grade ◽  
Potential Cost ◽  
Coating Deposition ◽  
Spray Coatings ◽  
Plasma Spray Coatings ◽  
Ld Slag

LD slag (LDS) is a major solid waste generated in huge quantities during steel making. It comes from slag formers such as burned lime/dolomite and from oxidising of silica, iron etc., while refining the iron into steel in the LD furnace. This work aims at utilization of waste LDS to develop surface coatings by plasma spraying technique. This technology has the advantage of being able to process various low-grade ore minerals to obtain value-added products and also to deposit materials, generating near homogeneous coatings with the desired microstructure. Coatings prepared for this investigation are characterized in terms of their thickness, hardness, adhesion strength and porosity. Coating deposition efficiency is calculated in order to assess the coatability of LDS and XRD is carried out in order to ascertain the various phases present in the coating. Premixing of TiO2 powder with LDS is found to substantially improve the interfacial adhesion. It is also found that the operating power levels of the plasma torch affect the adhesion strength, coating deposition efficiency and mean thickness of the coatings. This work reveals that LD slag is eminently coatable and can be gainfully used as a potential cost-effective material for deposition of plasma spray coatings on metallic substrates.

The Ultimate Spray Booth

1997 ◽  
Author(s):  
L. Pejryd ◽  
J. Wigren ◽  
N. Hanner
Keyword(s):  
Thermal Spray ◽  
Thermal Spraying ◽  
Thermal Spray Coatings ◽  
Design Element ◽  
Production Flow ◽  
Statistical Process ◽  
Spray Coatings ◽  
Spray Process ◽  
Spray Booth ◽  
On Line

Abstract Reproducibility is a current challenge for the thermal spray industry. Reproducibility associated problems represent a large cost every year not only in terms of rejections and rework, but also in costs for destructive testing and decreased production flow. Thermal spray coatings are moving in the direction of being considered only as a "band aid" to becoming a design element. One of the prerequisites for such a development is an increase in reproducibility for thermal spray coatings. The purpose of this paper is to outline a vision aiming in the direction of a future "ultimate spray booth", where thermal spraying is as reproducible and reliable as machining, grinding or other production processes. A way to increase reproducibility and reliability in the future spray shop involves utilising major parts of IT - technology. This also includes active co-operation design-production in the pre-spray process. This paper will deal with areas such as: operation drawings and lists through multimedia techniques, education programs for operators and designers through multimedia techniques, CAD/CAM, Off-line programming and simulation, On-line diagnostics of flame (particle diagnostics) and coating (temperature & Acoustic emission measurements), on-line Statistical Process Control and Knowledge Based System techniques.

Principles and Applications of Thermal Spray Coatings

2021 ◽  
pp. 31-70
Author(s):  
John Henao ◽  
Carlos A. Poblano-Salas ◽  
Fabio Vargas ◽  
Astrid L. Giraldo-Betancur ◽  
Jorge Corona-Castuera ◽  
...  
Keyword(s):  
Thermal Spray ◽  
Thermal Spraying ◽  
Industrial Applications ◽  
Thermal Spray Coatings ◽  
Flame Spray ◽  
Spray Coatings ◽  
Thermal Barriers ◽  
Energy Conversion Devices ◽  
Thermally Sprayed ◽  
Sprayed Coatings

The goal of the chapter is to address the fundamental theory of thermal spraying and its modern industrial applications, in particular, those involving flame spray, HVOF, plasma spray, and cold spray processes. During the last 30 years, thousands of manuscripts and various book chapters have been published in the field of thermal spray, displaying the evolution of thermally sprayed coatings in many industrial applications. Thermal spray coatings are currently interesting for different modern applications including prosthesis, thermal barriers, electrochemical catalysis, electrochemical energy conversion devices, biofouling, and self-repairing surfaces. The chapter will explain the fundamental principles of the aforementioned thermal spraying processes and discuss the effect of different controlling parameters on the final properties of the produced coatings. This chapter will also explore current and future industrial applications of thermal spray coatings.

An ASM Recommended Practice for Modified Layer Removal Method (MLRM) to Evaluate Residual Stress in Thermal Spray Coatings

2000 ◽  
Author(s):  
E.F. Rybicki ◽  
J.R. Shadley ◽  
R.T.R. McGrann ◽  
A.C. Savarimuthu ◽  
D. Graving
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Residual Stresses ◽  
Thermal Spray ◽  
Thermal Spray Coatings ◽  
Removal Method ◽  
Layer Removal ◽  
Spray Coatings ◽  
Layer Removal Method ◽  
Modified Layer

Abstract Thermal spray coatings are subjected to mechanical loadings in many applications, and there is a need to evaluate the mechanical properties of these coatings. Mechanical properties of interest in the performance of thermal spray coatings include fatigue life, wear resistance, bond strength. Young's modulus, Poisson's ratio, and residual stresses. One property that has a large effect on the performance of thermal spray coated parts is the residual stress distribution in the thermal spray coating and in the substrate. Thus, it is important to have (1) a fundamentally sound method for evaluating residual stresses and (2) a written recommended procedure for applying the method. ASM International is not a standard writing organization. Yet, the increased use of thermal spray coatings and the need for documentation on methods for evaluating mechanical properties of thermal spray coatings have generated a need to prepare Recommended Practices. To meet this need, the ASM International Thermal Spray Society has formed three subcommittees to prepare Recommended Practices for thermal spray coatings. This paper describes a draft form of a Recommended Practice for evaluating residual stresses in thermal spray coatings. This Recommended Practice is being developed by the Subcommittee on "Evaluating of Mechanical Properties of Thermal Spray Coatings". The method, called the Modified Layer Removal Method, has been presented in several papers and has been used for a variety of different coatings. The paper describes the dimensions of the test specimen, the equipment needed, the procedure for removing layers, and the methods for collecting and interpreting the data to evaluate through thickness residual stresses. The Recommended Practice (RP) is in Draft form, but is presented to let the thermal spray community know about the RP effort and invite comments and volunteers to write other RP's.

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