scholarly journals Coating thickness of the restored contact of electrical equipment and the method of its determination

2020 ◽  
pp. 28-44
Author(s):  
V. Korobsky ◽  
◽  
S. Sobol ◽  
S. Lapshin ◽  
◽  
...  
Keyword(s):  
Base Metal ◽  
Coating Thickness ◽  
Liquid Phase Sintering ◽  
Electrolytic Deposition ◽  
Transverse Displacement ◽  
Technological Characteristic ◽  
Advantages And Disadvantages ◽  
Linear Movement ◽  
Sprayed Coating ◽  
Sprayed Coatings

The regularities of the formation of the main variants of coatings obtained by gas-plasma spraying with subsequent liquid-phase sintering, depending on the conditions of wetting the powder particles with the melt and the porosity of the sprayed layer, have been established. The analysis of methods for controlling the thickness of thermal gas coatings, which indicates the advantages and disadvantages of three methods of measuring the thickness: magnetic, electromagnetic (eddy currents) and metallographic. The research of the dependence of the thermal power of the plasma jet (directly affects the thickness of the sprayed coating) on the thermal equivalent of the electric power of the arc was carried out; dependence is characterized by an effective efficiency. As a result of the research, the thickness of the sprayed coatings of the contacts and the tolerances for their processing were calculated depending on the height of the contact piece. Coating thickness is the shortest distance between the coating surface at a given point and the base metal surface. As a technological characteristic, the thickness affects such an important performance property as the strength of the bond with the base metal. Increasing the thickness of the coating above the optimum leads not only to a deterioration in quality (decrease in bond strength), but also to economic costs. The coating was applied to a given area due to the linear movement of the spray device in combination with either the transverse displacement of the spray device or contact piece. With a single linear movement of the spray device, the sprayed material forms a uniform coating layer, the cross-section of which is described by the Gaussian curve. The requirements for the thickness of the sprayed layer are indicated in the technological documentation, based on the uniformity of the distribution of the coating thickness on the contact surface. The required thickness of the sprayed coating was determined based on the thickness of the working layer, the tolerance for subsequent processing and the tolerance for the dimensions of the contact piece and the thickness of the sprayed layer. The thickness of the sprayed coating on the contacts, in which the lost dimensions are restored, provided for a tolerance for their following processing: turning and grinding. As a result, the thicknesses of the sprayed coatings of the contacts and the tolerances for their machining were calculated depending on the height of the contact piece (the number of switching cycles of the sprayed contact pieces). In thermal spraying of coatings, the build-up of parts occurs at a relatively high rate, that is, approximately 10 - 20 times faster than electrolytic deposition of steel and approximately 100 - 200 times faster than electrolytic chromium plating.

Sliding Wear Behavior of Remelted Al2O3-TiO2 Plasma Sprayed Coatings on Titanium

2016 ◽  
Vol 254 ◽  
pp. 231-236 ◽  
Author(s):  
Ion Dragoş Uţu ◽  
Gabriela Marginean ◽  
Iosif Hulka ◽  
Viorel Aurel Şerban
Keyword(s):  
Sliding Wear ◽  
Wear Behavior ◽  
Pure Titanium ◽  
Titanium Substrate ◽  
Atmospheric Plasma ◽  
Wear Properties ◽  
Before And After ◽  
Sprayed Coating ◽  
Pin On Disk ◽  
Sprayed Coatings

Microstructure and wear properties of the Al2O3-13.wt% TiO2 thermally sprayed coatings before and after remelting were investigated in this study. The coatings were deposited on a pure titanium substrate using the atmospheric plasma spraying (APS) process. The as-sprayed coatings were electron beam (EB) modified in order to improve their compactness and bonding strength.The effect of EB remelting on the microstructure, phase constituents and wear properties was investigated using scanning electron microscopy (SEM), X-Ray diffraction technique and hardness measurements. The sliding wear behavior was tested using a pin on disk method.The results showed that the remelting process had a positive effect removing the lamellar defect of the as-sprayed coating and improving the compactness, hardness and wear behavior.

Sealing Treatment of Plasma Sprayed Cr3C2-NiCr/Al2O3-TiO2 Coating by Aluminum Phosphate Sealant Containing Al2O3 Nanoparticles

2021 ◽  
Author(s):  
Tuan Nguyen Van ◽  
Tuan Anh Nguyen ◽  
Ha Pham Thi ◽  
Ly Pham Thi ◽  
Phuong Nguyen ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Electrochemical Impedance ◽  
Aluminum Phosphate ◽  
Al2o3 Nanoparticles ◽  
Treatment Efficiency ◽  
Typical Structure ◽  
Sprayed Coating ◽  
Plasma Sprayed ◽  
Sealing Treatment ◽  
Sprayed Coatings

Abstract A typical structure of thermal spray coatings consisted of molten particles, semi-molten particles, oxides, pores and cracks. These factors caused the porosity of sprayed coatings, leading to a great influence on the coating properties, especially their wear-corrosion resistance. In this study, a post-spray sealing treatment of Cr3C2-NiCr/Al2O3-TiO2 plasma sprayed coatings was carried out, then their corrosion properties were evaluated, before and after the treatment. For sealing process, aluminum phosphate (APP) containing aluminum oxide (Al2O3) nanoparticles (~10 nm) was used. The permeability of APP into the sprayed coating was analyzed by scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS). The treatment efficiency for porosity and corrosion resistance of sprayed coatings were evaluated by electrochemical measurements, such as the potentiodynamic polarization and electrochemical impedance spectroscopy. In addition, the wear-corrosion resistance of the sealed coating was examined in 3.5 wt.% NaCl circulation solution containing 0.25 wt.% SiO2 particles. The obtained results showed that APP penetrated deeply through the sprayed coating. The incorporation of Al2O3 nanoparticles into APP sealant enhanced the treatment efficiency of porosity for sprayed coating. The effect of the post-treatment on corrosion protection of the sprayed coating has been discussed.

Hard Arc-Sprayed Coating with Enhanced Erosion and Abrasion Wear Resistance

2000 ◽  
Author(s):  
S. Dallaire
Keyword(s):  
Ceramic Coatings ◽  
High Energy ◽  
Arc Spraying ◽  
Cored Wire ◽  
Industrial Sectors ◽  
Wear Protection ◽  
Abrasion Wear ◽  
Sprayed Coating ◽  
Impact Angles ◽  
Sprayed Coatings

Abstract Exposed to particle erosion environments, metal-sprayed coatings are damaged by micro-machining and ploughing at low impact angles. The generation and propagation of subsurface lateral cracks at high impacting angles damage single-phase ceramic coatings. Therefore, multicomponent coatings deposited by high-energy processes have been widely used to provide wear protection in most of the applications. As commercial arc-sprayed coatings have been used to a limited extent in applications involving erosion and abrasion wear, developing attractive wear resistant arc-sprayed coatings has been found necessary. A cored wire formulation, referred to as Alpha-1800, has been developed to produce tailored arc-sprayed coatings that are tough enough to resist particle impacts at 90° and sufficiently hard to deflect eroding particles at low impact angles. Typical 1 mm-thick coatings composed of ductile and hard phases with Knoop hardness reaching 1800 kg/mm2 were easily produced by arc spraying the cored wire with air. Coatings were: 1) erosion tested at 25°C and higher temperatures at impact angles of 25° and 90° in a gas-blast erosion rig, 2) slurry erosion tested at impact angles of 25° and 90°, 3) abrasion wear tested using the ASTM G-65 test procedure. Results show that coatings produced with the new cored wire are at least 5 times more erosion resistant and 10 times more abrasion resistant than coatings produced by arc spraying commercial cored wires. The performance of the new arc-sprayed coating can be compared with that of high-energy WC-based coatings. Being thermally stable up to 850°C, arc-sprayed coatings produced with the new cored wire are attractive for applications in many industrial sectors up to high temperatures.

Characterization of Structure of Thermally Sprayed Coating

1998 ◽  
Author(s):  
C.J. Li ◽  
Y. He ◽  
A. Ohmori
Keyword(s):  
Lamellar Structure ◽  
Structural Parameters ◽  
Lamellar Thickness ◽  
Pore Networks ◽  
Bonding Ratio ◽  
Sprayed Coating ◽  
The Relationship ◽  
Thermally Sprayed ◽  
Sprayed Coatings

Abstract The structure of a thermally sprayed coating is generally of lamellar structure. There is generally porosity in the coating. The examination shows that the relationship between properties and porosity for conventionally processed porous materials is difficult to be applied to thermally sprayed coating because of complex pore networks. The lamellar structure of the coating and the bonding at the interfaces between lamellae often determine the properties of coating. It is generally difficult to evaluate quantitatively the structure of a thermally sprayed coating because of complicated pore networks in the coating. With the filling of the material different from the composition of the coating into the pores the structure of the coating including nonbonded interface area and also generally referred pores can be visualized. According to the distribution of filler in the coating the structure of a coating can be quantitatively evaluated using structural parameters such as lamellar thickness, lamellar bonding ratio, the width of interface gap and so on. The structural parameters necessary to describe the lamellar structure of thermal sprayed coatings and a method based on the pore filling and analysis of the distribution of filled materials are proposed.

Electrolytic Solder Deposit for Next Generation Flip Chip Solder Bumping

2010 ◽  
Vol 2010 (DPC) ◽  
pp. 000671-000707
Author(s):  
Stephen Kenny ◽  
Sven Lamprecht ◽  
Kai Matejat ◽  
Bernd Roelfs
Keyword(s):  
Flip Chip ◽  
Practical Experience ◽  
Electrolytic Deposition ◽  
Solder Paste ◽  
Stencil Printing ◽  
Printing Process ◽  
Advantages And Disadvantages ◽  
Novel Approach ◽  
Solder Bumps ◽  
Chip Attachment

Electrolytic Solder Deposit for Current methods for the formation of pre-solder bumps for flip chip attachment use stencil printing techniques with an appropriate solder paste. The continuing trend towards increasing miniaturisation and the associated decrease in size of solder resist opening, SRO is causing production difficulties with the stencil printing process. Practical experience of production yields has shown that stencil printing will not be able to meet future requirements for solder bump pitch production below 0.15 mm for these applications. This paper describes a novel approach to replace the stencil printing process by use of an electrolytic deposition of solder. In contrast to stencil printing, use of electrolytic deposition techniques allows production of solder bumps with a pitch below 0.15 mm and with a SRO below 80 μm. Methods for production of electrolytic solder bumps based on pure tin as well as alloys of tin/copper and also tin/silver are shown and in particular a method to control the alloy concentration of electroplated tin/copper bumps. Test results with both alloy systems and also pure tin bumping are presented together with comparison of the advantages and disadvantages. The general advantages of replacement of stencil printing by electrolytic deposition of solder bumps are shown and in particular the improvement of bump reliability and the potential to significantly decrease costs by yield improvement.

Dry Surface Preparation Using Supercritical Cryogenic Nitrogen Jet Improves the Adhesion Strength of Cold Gas Sprayed Coatings (SCNCS)

2018 ◽  
Vol 941 ◽  
pp. 1668-1673
Author(s):  
Abdel Tazibt ◽  
Guillaume Ezo'o ◽  
Yosri Khalsi ◽  
Mustapha Yahiaoui
Keyword(s):  
Surface Preparation ◽  
Cold Spraying ◽  
Substrate Preparation ◽  
Preparation Methods ◽  
Adhesion Performance ◽  
Pulsed Water Jet ◽  
Sprayed Coating ◽  
Sprayed Coatings ◽  
Required Quality

The adhesion performance of Cold Sprayed coatings depends on the quality of the substrate [1,2,4,8]. Before deposition, the surface of substrate must be prepared to a specific required quality, which promotes the anchoring of sprayed coating. Grit Blasting (Samson et al.) [1] is known as the conventional surface preparation before Cold Spraying. But such method causes issues: a) shallow roughness, which does not strengthen bonds between layer and substrate; b) embedment of particles in the substrate, which creates discontinuity of the material at the interface and causes cracks that degrade the layer. Recently, Laser [2] and Pulsed Water Jet (PWJ) [1] have been tested as substrate preparation methods. These methods have shown their ability to generate improved roughness without particle embedment. PWJ has particularly shown interest in Al substrate to generate crevices, which are anchors for the Cold Sprayed coatings. Nevertheless, Laser affects thermally the substrate and induces constraints that may disadvantage the coating quality. PWJ generates liquid effluents. Besides some substrates such as ferrous metals can react with oxygen of water leading to corrosion and coating adhesion weakness.

scholarly journals Active IR Thermography Evaluation of Coating Thickness by Determining Apparent Thermal Effusivity

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4057
Author(s):  
Alexey Moskovchenko ◽  
Vladimir Vavilov ◽  
Michal Švantner ◽  
Lukáš Muzika ◽  
Šárka Houdková
Keyword(s):  
Coating Thickness ◽  
Analytical Modeling ◽  
Thermal Effusivity ◽  
Threshold Value ◽  
Ir Thermography ◽  
Pulsed Thermography ◽  
Thermally Sprayed Coatings ◽  
Common Technique ◽  
Thermally Sprayed ◽  
Sprayed Coatings

Pulsed thermography is a common technique for nondestructive testing (NDT) of materials. This study presents the apparent effusivity method for the quantitative evaluation of coating thickness in a one-sided thermal NDT procedure. The proposed algorithm is based on determining a threshold value of apparent effusivity, which can be found for particular coating-on-substrate structures. It has been found that the square root of the time at which the apparent effusivity curve reaches this threshold is proportional to the coating thickness. The efficiency of the proposed approach is demonstrated by analytical modeling and experimentation performed on thermally-sprayed coatings.

Effect of Annealing Treatment on the Structure and Microhardness of Cold-Sprayed Nanostructured FeAl/WC Composite Coating

2008 ◽  
Vol 373-374 ◽  
pp. 73-76 ◽  
Author(s):  
Hong Tao Wang ◽  
Guan Jun Yang ◽  
Chang Jiu Li ◽  
Cheng Xing Li
Keyword(s):  
Solid Solution ◽  
Annealing Time ◽  
Composite Coatings ◽  
Annealing Treatment ◽  
Nanocrystalline Structure ◽  
Intermetallic Phases ◽  
Coating Structure ◽  
Intermetallic Composite ◽  
Sprayed Coating ◽  
Sprayed Coatings

Nanostructured FeAl/WC intermetallic composite coatings were prepared by cold spaying of the ball-milled powders. The effect of annealing on the coating structure and microhardness was examined. It was found that the nanocrystalline structure of the milled feedstock was retained in the cold sprayed coatings. The FeAl intermetallic phases were formed from the milled Fe(Al) solid solution during the post-spraying annealing at 550oC. The microhardness of the as-sprayed coating was about 680HV0.1 and it decreased a little with increasing the annealing time at 550oC.

Residual Stress Measurement of Plasma Sprayed Coating Layers in ZrO2

2007 ◽  
Vol 544-545 ◽  
pp. 451-454
Author(s):  
Soo Wohn Lee ◽  
Jia Zhang ◽  
Huang Chen ◽  
J. S. Song ◽  
Jae Kyo Seo ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Measurement ◽  
Diffraction Method ◽  
Spray Coating ◽  
X Ray Diffraction ◽  
Plasma Sprayed Coatings ◽  
Coating Layers ◽  
Sprayed Coating ◽  
Plasma Sprayed ◽  
Sprayed Coatings

Plasma sprayed coatings have been widely applied in modifying surface properties of metal components. It is also useful to prevent various types of wear, corrosion, erosion and thermal. But the residual stress is still an important problem which can effect the properties of sprayed coating. So it’s necessary to find out the reason of residual stress and the relationship between plasma sprayed condition and residual stress. Plasma spray coating layers with conventional ZrO2 powder was examined to calculate residual stress by X-ray diffraction method with various coating thickness.

Simplified models for residual stress prediction in thermally sprayed coatings

2008 ◽  
Vol 222 (11) ◽  
pp. 2053-2068 ◽  
Author(s):  
A M Kamara ◽  
K Davey
Keyword(s):  
Residual Stress ◽  
Layer Thickness ◽  
Coating Thickness ◽  
Interfacial Stress ◽  
Analytical Models ◽  
Elastic Behaviour ◽  
Layer Deposition ◽  
Thermally Sprayed Coatings ◽  
Thermally Sprayed ◽  
Sprayed Coatings

Residual stress in thermally sprayed coatings is known to cause a range of problems, notably debonding, cracking, and spallation. The focus in this paper is on the development of simple analytical models for the prediction of residual stress that arise from spraying a steel-alloy coating onto a copper-alloy substrate. This is a material combination that has been used recently to enhance the thermal and mechanical efficiency of the pressure die casting process although problems with debonding have been reported in the literature. Three analytical models are developed and investigated, where each represent combinations of assumptions for coating and substrate material behaviours during coating manufacture. The sensitivity of these combinations on residual stress, developed for a range of process parameters (deposited layer thickness, interval of layer deposition and the number of layers in a coating, i.e. block deposition versus multi-layer deposition for a desired coating thickness) is recorded. In agreement with experimental and finite-element modelling results from a previous study, the results from all the three models assessed in the current study indicate a progressive change in average interfacial residual stress from compressive towards tensile with an increase in the thickness of the deposited layer; and a tensile interfacial stress in a two-layer coating, which increases with an increase in the interval of deposition between the two layers. The observations from the results suggest an increase in potential for coating debonding with an increase in both deposited layer thickness and layer deposition interval. The results further suggest higher potential for coating debonding with block deposition compared with multi-layer deposition for a desired coating thickness. In terms of stress magnitudes, the model that performs best is one where the assumption that a currently deposited coating layer yields during its quenching phase and adopts elastic behaviour afterwards; and the strain generated in the substrate during the quenching phase is from thermal effect only while in the other phases afterwards, is from both thermal and elastic effects.

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