Temperature Profiles and Thermal Stress Analysis of Plasma Sprayed Glass-Composite Coatings

2000 ◽  
Author(s):  
T. Zhang ◽  
Z. Qiu ◽  
Y. Bao ◽  
D.T. Gawne ◽  
K. Zhang
Keyword(s):  
Thermal Stress ◽  
Volume Fraction ◽  
Spray Deposition ◽  
Steel Substrate ◽  
Composite Coatings ◽  
Operating Conditions ◽  
Second Phase ◽  
Temperature Profiles ◽  
Glass Composite ◽  
Phase Volume Fraction

Abstract Experimental measurements have been carried out with the aim of investigating the residual stresses generated during plasma spray deposition of glass composite coatings. The research shows that the behaviour of these materials is fundamentally different from metals and ceramics. The quench stress in the glass composites can be eliminated by plasma-scanning. This is attributed to their low glass transition temperatures, which enable the stresses to be completely relaxed. The work also shows that the addition of alumina as a second phase allows the expansion mismatch between the coating and the steel substrate to be controlled. Control of the second-phase volume-fraction enables the residual stress in the composite coatings to be reduced to zero. Real-time measurements on deflection and temperature show that the dimensions of the substrate, plasma operating conditions and scanning rate have substantial effects on the temperature profiles within the deposits. Keywords: glass composite coatings, thermal stress, plasma spraying.

Effect of Solution Treatment Temperature on Microstructure and Mechanical Properties of Al-5.1Zn-2Mg-0.1Ti (wt. %) Produced by Squeeze Casting

2018 ◽  
Vol 939 ◽  
pp. 38-45 ◽  
Author(s):  
Risly Wijanarko ◽  
Irene Angela ◽  
Bondan Tiara Sofyan
Keyword(s):  
Squeeze Casting ◽  
Volume Fraction ◽  
Solution Treatment ◽  
Treatment Temperature ◽  
Ageing Process ◽  
Al Alloy ◽  
Second Phase ◽  
Solution Treatment Temperature ◽  
Phase Volume Fraction ◽  
Ti Addition

Al 7xxx alloy is a heat treatable Al alloy with superior strength. Solution treatment in precipitation hardening sequence of the alloy has an important role to dissolve second phases and bring vacancies out to form precipitates in the ageing process. Another strengthening can be done by Ti addition as grain refiner. As cast alloy by squeeze casting was homogenized at 400 °C for 4 h. Solution treatment was conducted at 220, 420, and 490 °C, followed by rapid quenching. Subsequent ageing was conducted at 130 °C for 48 h. Characterization was performed by optical microscope, SEM-EDS (Scanning Electron Microscopy – Energy Dispersive Spectroscopy), Rockwell hardness testing, XRD (X-Ray Diffraction), and STA (Simultaneous Thermal Analysis). Ti added alloy showed rounder grains, lower hardness, and more reduction in second phase volume fraction along with increasing solution treatment temperature than those in alloys without Ti addition. Otherwise, the alloy final hardness was increasing and higher after the ageing process due to higher second phase dissolution which leads to more precipitates formed.

Abnormal Grain Growth in Metals

2007 ◽  
Vol 558-559 ◽  
pp. 717-722 ◽  
Author(s):  
J. Dennis ◽  
Pete S. Bate ◽  
John F. Humphreys
Keyword(s):  
Grain Growth ◽  
Volume Fraction ◽  
Abnormal Grain Growth ◽  
Grain Structure ◽  
Second Phase ◽  
Boundary Misorientation ◽  
Phase Volume Fraction ◽  
Abnormal Growth ◽  
Grain Boundary Misorientation ◽  
Dominant Characteristic

Grain growth may occur in two forms, normal grain growth, characterized by a constant grain size distribution during growth, and abnormal grain growth, where one or more abnormally large grains may form in the microstructure. The presence of abnormally large grains in an otherwise uniform microstructure may be detrimental to the mechanical properties of a polycrystalline structure. Little is understood of the exact cause of abnormal grain growth. The annealing conditions leading to the onset of abnormal grain growth have been investigated via a series of grain growth experiments carried out on an Al-4wt%Cu alloy. The structure of which consisted of equiaxed grains (<8μ) pinned by a fine dispersion of sub-micron second phase particles, which may dissolve upon annealing. Minority texture components may experience accelerated growth due to a higher energy and mobility compared to the surrounding grain structure. The combination of these two events may result in the abnormal growth of some grains. SEM imaging and EBSD data has then made it possible to characterize the influence of particle dissolution and grain boundary misorientation on the onset of abnormal grain growth. The stability of ‘island grains’ found to exist internally in abnormally large grains has also been investigated in relation to the misorientation relationship and localized second phase volume fraction found there. There was only weak evidence of special misorientation relationships between the island grains and the abnormally large grains in which they exist, and although there was evidence of an enhanced fraction of pinning particles at island grain boundaries, this was also true of boundaries in general. The larger size of island grains is their dominant characteristic, and grains which become island grains may have been incipient abnormal grains.

MICROSTRUCTURE AND PROPERTIES OF IN SITU SYNTHESIZED ZrC-ZrB2/Fe COMPOSITE COATING PRODUCED BY GTAW

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1438-1443 ◽  
Author(s):  
ZHENTING WANG ◽  
LILI CHEN ◽  
XIANYOU ZHANG
Keyword(s):  
Wear Resistance ◽  
Composite Coating ◽  
Volume Fraction ◽  
Steel Substrate ◽  
Composite Coatings ◽  
Energy Dispersive Spectrum ◽  
X Ray Diffraction ◽  
Gas Tungsten Arc ◽  
C 30

A metal matrix composite coating reinforced by ZrC - ZrB 2 particulates has been successfully fabricated utilizing the in situ reaction of Zr , B 4 C and Fe pre-placed mixed powders by gas tungsten arc welding (GTAW) cladding process. Various volume fraction of ZrC - ZrB 2 particulates composite coatings were produced through cladding different weight ratios of Zr + B 4 C (30%, 50%, 70%) to improve the wear resistance of AISI1020 steel substrate. The Microstructure of the coating was analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive spectrum (EDS), meantime microhardness and wear resistance at room temperature of the composite coating were examined by means of Microhardness Tester and Wear Tester, respectively. The results show that the main phases of the composite coating obtained by GTAW are ZrC , ZrB 2 and α- Fe , ZrC exhibits hexahedron and petal shapes, ZrC - ZrB 2 compound presents acicular and clubbed forms. With the increase of content of Zr + B 4 C , the maximum volume fraction of ZrC - ZrB 2 particulates can reach 16.5%, microhardness is up to 1300HV, and wear resistance is about twenty times higher than that of AISI1020 steel substrate.

Influence of Addition of Tungsten-Iron Powder on Microstructure of WC/Steel Composite Coatings

2012 ◽  
Vol 463-464 ◽  
pp. 394-398
Author(s):  
Zu Lai Li ◽  
Zhi Hui Chen ◽  
Ye Hua Jiang ◽  
Rong Zhou ◽  
Quan Shan ◽  
...  
Keyword(s):  
Iron Powder ◽  
Volume Fraction ◽  
Steel Substrate ◽  
Composite Coatings ◽  
Interfacial Strength ◽  
Optical Microscope ◽  
Steel Matrix ◽  
Casting Technique ◽  
The Matrix ◽  
Reinforced Steel

The casting WC particles reinforced steel matrix composite coatings on Cr15 steel substrate were fabricated using the vacuum infiltration casting technique, meanwhile, investigated the relationship between the structure, hardness and the volume fraction of tungsten-iron powder in the composite coatings. The fabricated composite coatings contained tungsten-iron powder of 4.96, 9.31, 17.15 and 23.64 vol%, respectively. The microstructures and phase of the composite coatings were analyzed using Optical Microscope (OM), Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD). The results shows that, with increase in volume fraction of tungsten-iron powder, the amount of martensite and in situ synthesized Fe3W3C have increased. The changes of the hardness in the composite coatings with the volume fraction of tungsten-iron powder, and the hardness has been improved greatly, the highest hardness value can reach HRC 65. In addition, the reacted layers have been formed around the WC particles and mainly consist of Fe3W3C, therefore, the interfacial strength is increased significantly. However, tungsten element in the matrix hampered the melting of the WC particles.

Hardness Regulation of Fe-Based Amorphous Composite Coatings by Laser Remelting

2014 ◽  
Vol 789 ◽  
pp. 64-69 ◽  
Author(s):  
Yong Tian Wang ◽  
Ming Ming Yuan ◽  
Jing Kang Duan ◽  
Run Sen Jiang ◽  
Lin Hu ◽  
...  
Keyword(s):  
Composite Coating ◽  
Laser Power ◽  
Volume Fraction ◽  
Steel Substrate ◽  
Composite Coatings ◽  
Power Input ◽  
Arc Spraying ◽  
Laser Remelting ◽  
Application Fields

A Fe-based amorphous composite coating was deposited on a carbon steel substrate by arc spraying, and remelted with different laser energies by the Nd: YAG laser cladding system, in order to improve the mechanical properties of the coatings. The microstructure and microhardness of the composite coatings were investigated. The variation of harndness was measured as a function of the modified layer depth, which indicates that the laser remelting improves the bonding strength and hardness. Increasing the laser power, the quality of coating gets better, but the amorphous volume fraction decreases. It is obtained that the optimal laser electric current for the coating of 280 μm thickness is about 300 A, in which the remelted coating with medium energy densities has the highest average Vickers hardness of 741. Through the volume fraction change of the nanocrytals, the hardness of the composite coating is regulated by the laser power input, which amplified the application fields of the amorphous coatings.

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