Microstructure and wear properties of Fe–TiC surface composite coating by laser cladding (original) (raw)
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Surface and Coatings Technology, 2008
Titanium carbide particles reinforced Fe-based surface composite coatings were fabricated by laser cladding using a 5 kW CO2 laser. The microstructure, phase structure and wear properties were investigated by means of scanning electron microscopy, transmission electron microscopy and X-ray diffraction, as well as dry sliding wear test. The results showed that TiC carbides were formed via in situ reaction between ferrotitanium and graphite in the molten pool during the laser-clad process. The morphology of TiC is mainly cubic and dendritic form; and the TiC carbides were distributed uniformly in the composite coating. The TiC/matrix interface was found to be free from cracks and deleterious phases. The coatings reinforced by TiC particles revealed higher wear resistance and lower friction coefficient than that of the substrate and FeCrBSi laser-clad coating.
Optics and Lasers in Engineering, 2010
In this study, in situ multiple carbides reinforced Fe-based surface composite coatings were fabricated successfully by laser cladding a precursor mixture of graphite, ferrotitanium (Fe-Ti) and ferromolybdenum (Fe-Mo) powders. The results showed that (Ti, Mo)C particles with flower-like and cuboidal shapes were in situ formed during the solidification and most shapes of (Ti, Mo)C particles were diversiform according to different contents of Fe-Mo powder in the Fe-Ti-Mo-C system. The growth morphology of the reinforcing (Ti, Mo)C carbide has typically faceted features, indicating that the lateral growth mechanism is still predominant growth mode under rapid solidification conditions. Increasing the amount of Fe-Mo in the reactants led to a decrease of carbide size and an increase of volume fraction of carbides. The coatings had good cracking resistance when the amounts of Fe-Mo were controlled within a range of 15 wt%.
Engineering, Technology & Applied Science Research
Spheroidal graphite cast iron was laser cladded with TiC powder using a YAG fiber laser at powers of 700, 1000, 1500 and 2000 W. The powder was preplaced on the surface of the specimens with 0.5 mm thickness. Sound cladding and fusion zones were observed at 700, 1000 and 1500 W powers. However, at 2000 W, cracking was observed in the fusion zone. At 700 W, a build-up zone consisted of fine TiC dendrites inside a matrix composed of martensite, cementite (Fe3C), and some blocks of retained austenite was observed. In this zone, all graphite nodules were totally melted. In the fusion zone, some undissolved and partially dissolved graphite nodules appeared in a matrix containing bainite, ferrite, martensite and retained austenite. At 1500 W, the fusion zone had more iron carbides and ferrite, and the HAZ consisted of martensitic structure. At 2000 W, the build-up zone was consisted of TiC particles precipitated in a matrix of eutectic carbides, martensite plus an inter-lamellar retaine...
Metallurgical and Materials Transactions B, 2016
Laser cladding was used to produce surface composite layer reinforced with TiC particles on low-carbon steel alloy for improving the wear and corrosion resistances. The cladding process was carried out at powers of 2800, 2000, 1500, and 1000 W, and a fixed traveling speed of 4 mm/ s. The produced layers are free from any cracks. Some of the TiC particles were melted and then re-solidified in the form of fine acicular dendrites. The amount of the melted TiC was increased by increasing the laser power. The hardness of the produced layers was improved by about 19 times of the base metal. Decreasing laser power led to hardness increment at the free surface. The improvement in wear resistance was reached to about 25 times (in case of 1500 W) of the base metal. Moreover, the corrosion resistance shows remarkable improvement after the laser treatment.
Solidification microstructure of in-situ laser-synthesized Fe-TiC hard coating
Surface and Coatings Technology, 2016
Synthesis of Fe-TiC hard coatings on carbon steel substrates was the subject of several researches in previous decades. Various microstructural aspects were mentioned about the matrix and hard particles, therefore a more comprehensive perspective is required for investigation of the microstructures. In this study, a new method was applied for in-situ synthesis of Fe-TiC composite coating. The TiC particles were produced by laser surface treatment of a precursor of ilmenite and graphite powders. By progress of solidification front from substrate to surface, different microstructures were developed in the matrix, including
Fabrication of Laser Deposited TiC/Steel Matrix Composite Coatings
2003
The present work investigates the effect of laser scanning beam speeds and the content of TiC in injected powder on morphologies and microstructures of laser deposited beads of a TiC/H13 tool steel composite. The results show that the beam scanning speeds affect the size and morphology of the beads. During laser processing, TiC melts, decomposes, and subsequently, a number of fine TiC precipitates form during cooling that are uniformly distributed in the tool steel matrix. The beam scanning speeds and the amount of injected TiC exert a strong influence on the morphology and size of the fine TiC precipitates. It is believed that the precipitated TiC is the primary phase in hypereutectic Fe-TiC. Rapid cooling develops martensite with retained austenite in a steel matrix. The precipitated TiC can refine grains of the steel matrix as a solidified nucleus. TiC/H13 tool steel composite coatings with various contents of TiC were produced using the laser deposition processing technique.
Surface and Coatings Technology, 2014
High temperature wear properties of titanium carbide (TiC) composite coatings fabricated by laser cladding with titanium powder and varied percentages of carbon nano-tube (CNT) powders on titanium substrates have been tested by pin-on-disk wear under dry sliding conditions. The results reveal that TiC composite coatings fabricated with proper addition of CNT give promising high temperature wear resistance which is ten times higher than that of the titanium substrate. The high temperature wear behavior and friction coefficient of the titanium substrate and the composite coatings were investigated. It was found that the wear behavior of the dominant wear mechanism of the TiC composite coatings is adhesive wear and oxidation, whereas the Ti substrate exhibits abrasive wear, adhesive wear, serious plastic deformation, and oxidation at high temperature. The improvement of the wear resistance is believed to be attributed to the reinforcement phase of TiC which can also provide high hardness according to the microstructure observation of the composite coatings by SEM, EDX and microhardness measurements.
Laser assisted titanium carbide (TiC) coating on AISI304 stainless steel
2013
The increasing interest in the betterment of wear resistance and hardness of surfaces that are in contact with abrasives or corrosive materials has accelerated the development of several techniques for creating protective coatings. In this project a search is done on what can be the possible coatings and which are the substrates over which this coating is feasible. TiC was found to be exhibiting a very high melting point and thermal stability, high hardness and excellent wear resistance, low coefficient of friction and high electrical and thermal conductivities and hence chosen to be the best coating available. The substrate that is chosen for coating is AISI304 stainless steel. For the laser treatment pulsed Nd-YAG laser is used. After the laser coating operation the phase changes was studied under SEM. Composition of the laser clad layers was obtained by XRD and the hardness was measured by using Vickers microhardness tester. The hardness of the coating increased to a substantial ...
Microstructure and wear behavior of laser cladding VC–Cr7C3 ceramic coating on steel substrate
Materials & Design, 2013
A composite coating with enhanced mechanical properties including high hardness and excellent wear resistance was produced by laser cladding of mixed Ni45 and high-carbon ferrochrome powders on an ASTM 1045 steel substrate. Different quantities, ranging from 10 to 50 wt.% of high-carbon ferrochrome powder were added to the Ni45 powder to investigate the effect of mixture content on the cladding performance. The microstructure of the coatings were examined using scanning electron microscope, and the wear resistance was compared using a wear tester apparatus among the different cases. The results showed that the microstructure of the coating with 30 wt.% high-carbon ferrochrome content was mainly fine solid solution phase. With the increase of high-carbon ferrochrome content to 40 wt.% and above, cracks appeared on the cladding surface due to a large amount of chromium carbides formed during the process. The microhardness was enhanced remarkably by laser cladding the composite coating on the 1045 substrate, with 2.4 times higher than the hardness of the substrate when 30 wt.% high-carbon ferrochrome content was added. The best wear performance was achieved when the high-carbon ferrochrome content was 30 wt.%, demonstrating the smallest surface roughness and depth of wear marks. With further increased high-carbon ferrochrome content, microcracking and delamination were observed on the worn surfaces.