Microstructure, mechanical and wear properties of laser processed SiC particle reinforced coatings on titanium (original) (raw)
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Laser processing of SiC-particle-reinforced coating on titanium
Scripta Materialia, 2010
Laser engineered net shaping has been used to create a Ti-SiC composite layer on Ti to improve its wear resistance. The influences of laser power and scanning speed on the microstructure and wear resistance of the coatings were examined. Laser parameters were found to have a strong influence on the dissolution of SiC, leading to the formation of Ti 5 Si 3 and TiC with a high amount of SiC on the surface. The composite coatings with hardness between 976 and 1167 HV exhibited average wear rate between 5.91 and 6.60 Â 10 À4 mm 3 (N m) À1 .
Intermetallics, 2014
Transition metal silicides and carbides are attractive advanced materials possessing unique combinations of physical and mechanical properties. However, conventional synthesis of bulk intermetallics is a challenging task because of their high melting point. In the present research, titanium carbides and silicides composites were fabricated on the titanium substrate by a selective laser melting (SLM) of Ti e(20,30,40 wt.%)SiC powder mixtures by an Ytterbium fiber laser with 1.075 mm wavelength, operating at 50 W power, with the laser scanning speed of 120 mm/s. Phase analysis of the fabricated coatings showed that the initial powders remelted and new multiphase structures containing TiC x , Ti 5 Si 3 C x , TiSi 2 and SiC phases in situ formed. Investigation of the microstructure revealed two main types of inhomogeneities in the composites, (i) SiC particles at the interlayer interfaces and, (ii) chemical segregation of the elements in the central areas of the tracks. It was suggested and experimentally proven that an increase in laser power to 80 W was an efficient way to improve the laser penetration depth and the mass transport in the liquid phase, and therefore, to fabricate more homogeneous composite. The SLM Ti e(20,30,40 wt.%)SiC composites demonstrated high hardness (11e17 GPa) and high abrasive wear resistance (3.99 Â 10 À7 e9.51 Â 10 À7 g/Nm) properties, promising for the applications involving abrasive wear.
Microstructure and wear studies of laser clad Al-Si/SiC(p) composite coatings
Surface and Coatings Technology, 2007
Coatings of a composite material consisting of an Al-Si matrix reinforced with SiC particles were produced by laser cladding on UNS A03560 cast Al-alloy substrates from mixtures of powders of Al-12 wt.% Si alloy and SiC. The influence of the processing parameters on the microstructure and abrasive wear resistance of the coatings was studied. For an interaction time of 0.08 s and a power density of 330 MW/m 2 , corresponding to a specific energy of 26 MJ/m 2 , the interaction between SiC and liquid Al is limited and the reinforcement particles remain essentially undissolved. The coating's microstructure is formed of SiC particles dispersed in a matrix consisting of primary α-Al dendrites and interdendritic α-Al + Si eutectic. For interaction times of 0.3 and 0.45 s and a power density of 193 MW/m 2 , corresponding to specific energies of 58 and 87 MJ/m 2 , SiC reacts with molten Al and partially dissolves. The resulting microstructure consists of undissolved SiC particles, found mainly at the bottom of the clad tracks, where the maximum temperature reached during processing is lower, and Al 4 SiC 4 and Si particles dispersed in a matrix of α-Al + Si eutectic. The coatings prepared with higher specific energy (58 MJ/m 2 ) present a hardness of 250 V and an abrasive wear rate in three-body abrasion tests with SiC as abrasive of 1.7 × 10 − 4 mm 3 /m, while those produced with 26 MJ/m 2 present a hardness of 120 V and a wear rate of 0.43 × 10 − 4 mm 3 /m. These results show that Al 4 SiC 4 and Si increase the hardness of the material by dispersion hardening but do not contribute to its abrasive wear resistance, because they are softer than the abrasive particles, and confirm that the parameters used to prepare Al-Si-SiC composite coatings by laser cladding must be selected so that only minimal reactions occur between SiC and molten Al.
The microstructure of Fe 30 Ni 20 Mn 20 Al 30 in both the as-cast condition and after annealing at 823 K for various times up to 72 h was characterized using transmission electron microscopy, scanning transmission electron microscopy, synchrotron-based X-ray diffraction, and atom probe tomography. The microstructure exhibited a basketweave morphology of (Mn, Fe)-rich B2-ordered (ordered b.c.c.) and (Ni, Al)-rich L2 1 -ordered (Heusler type) phases with a lattice misfit of only 0.85 % and interfaces aligned along h100i. The phase width increased from 5 nm for the as-cast alloy to 25 nm for 72 h annealed material, with no change in the elemental partitioning between the phases, with a time exponent for the coarsening kinetics of 0.19. Surprisingly, it was found that the room temperature hardness was largely independent of the phase width.
Surface Engineering, 2018
The Ti-SiC-ZrB2 cermet coatings were fabricated on Ti6Al4 V by laser cladding with a 4 kW continuous wave Rofin Sinar Nd:YAG laser system. Three compositions of the cermet coatings of varying percentages of ZrB2 (0 wt-%, 5 wt-% and 10 wt-%) were added. Scanning electron microscopy and energy dispersive spectroscopy were used to study the microstructure of the coatings while X-ray diffractometry was utilised to investigate the existing phases on the coatings. The microstructures of the coatings were majorly characterised by secondary precipitates of granular TiC and Ti 5 Si 3 in β-Ti matrix. With the addition of ZrB2, new phases developed which were dispersed. This resulted in a corresponding increase in surface hardness where the resultant hardness values of the laser clad coatings were found to be approximately four times higher than Ti6Al4 V alloy.
Laser initiated Ti 3 SiC 2 powder and coating synthesis
Ceramics International, 2018
In the work the SHS synthesis of MAX phases from Ti-Si-C system were carried and initiated with use of 30 W laser beam with 40 µm spot. That kind of initiation allows locally and rapidly start the SHS synthesis and avoid the contamination coming from heating wire present during conventional method. The reaction was monitored by high-accuracy radiation pyrometer and high quality optical camera. The recorded data, together with reaction bed thermal conductivity measurements allowed to correlate to obtained powders composition and reaction speed. The reaction bed morphology was investigated by scanning electron microscopy with element distribution (EDS). The second part of the paper concerns laser reactive deposition of SHS in-situ synthetized MAX phases layer on silicon carbide substrate. The paths of deposited layer were formed under argon overpressure of 2 bar using 120 W of laser power.
Materials Science and Engineering: A, 2006
The present study concerns development of a hard SiC dispersed composite layer on an Al substrate to improve its wear resistance property. A thin layer of SiC (dispersed in alcohol) is pre-deposited (thickness of 100 m) on an Al substrate and laser irradiated using a high power continuous wave (CW) CO 2 laser. Irradiation of the pre-deposited Al substrate leads to melting of the substrate with a part of the pre-deposited SiC layer, intermixing and rapid solidification to form the composite layer on the surface. Following laser irradiation, a detailed characterization of the composite layer is undertaken in terms of microstructure, composition and phases. Mechanical properties like microhardness and wear resistance are evaluated in detail. The microstructure of the composite layer consists of a dispersion of partially melted SiC particles in a grain refined Al matrix. SiC particles are partly dissociated into silicon and carbon leading to formation of a low volume fraction of Al 4 C 3 phase and free Si redistributed in the Al matrix. The volume fraction of SiC is maximum at the surface and decreases with depth. The microhardness of the surface is improved by two to three times as compared to that of the as-received Al. A significant improvement in wear resistance in the composite surfaced Al is observed as compared to the as-received Al. The pitting corrosion property (in a 3.56 wt.% NaCl solution) is marginally deteriorated by laser composite surfacing.
Optics & Laser Technology, 2017
Ti 5 Si 3 /TiC reinforced Co-based composite coatings were fabricated on Ti-6Al-4V titanium alloy by laser cladding with Co42 and SiC mixture. Microstructure and wear property of the cladding coatings with different content of SiC were investigated. During the cladding process, the original SiC dissolved and reacted with Ti forming Ti 5 Si 3 and TiC. The complex in situ formed phases were found beneficial to the improvement of the coating property. Results indicated that the microhardness of the composite coatings was enhanced to over 3 times the substrate. The wear resistance of the coatings also showed distinct improvement (18.4-57.4 times). More SiC gave rise to better wear resistance within certain limits. However, too much SiC (20 wt%) was not good for the further improvement of the wear property.
Laser composite surfacing of stainless steel with SiC
Physica Status Solidi (a), 2006
In the present study, an attempt has been made to improve wear resistance of AISI 304 stainless steel by laser composite surfacing with SiC. Laser processing has been carried out by pre-deposition of Fe + SiC powders (in the ratio of 85:15 and thickness of 100 μm) on AISI 304 stainless steel substrate and subsequently, melting it using a 2 kW continuous wave CO2 laser. Following laser processing, a detailed characterization and evaluation of mechanical/electrochemical properties of the composite layer were undertaken to study the influence of laser processing on the characteristics and properties of the composite layer. Microstructure of the composite layer consisted of uniformly dispersed SiC particles in grain refined α-Fe dendrites. Laser composite surfacing led to a significant improvement in microhardness and wear resistance as compared to as-received substrate. However, pitting corrosion property was marginally deteriorated due to laser composite surfacing. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Surface and Coatings Technology, 2009
The influence of powder particle injection velocity on the microstructure of coatings consisting of an Al-Si matrix reinforced with SiC particles prepared by laser cladding from mixtures of powders of Al-12 wt.% Si alloy and SiC was investigated both experimentally and by modeling. At low injection velocities SiC particles react with the molten aluminum alloy. Only a small fraction of SiC remains in the microstructure, which contains large amounts of particles of the reaction products Al 4 SiC 4 and Si dispersed in the α-Al + Si eutectic matrix. By contrast, at high injection velocities chemical reactions between SiC and molten aluminum are almost entirely suppressed and the resulting microstructure consists only of SiC particles dispersed in the matrix. To investigate whether this behavior could be explained by the different temperatures reached by the injected particles as they fly through the laser beam, a physical-mathematical model describing the interaction between the laser beam and the powder stream in the off-axis blown powder laser cladding process was developed and applied to calculate the temperature attained by the powder particles as a result of their interaction with an Nd:YAG laser beam (λ = 1.06 µm). At an injection velocity of 1 m/s the maximum temperature attained by SiC and Al-12Si particles is 3150 and 180 ºC, respectively. This result demonstrates that particle injection velocity is a major parameter affecting the microstructure of coatings produced by laser cladding, and must be carefully controlled.