In situ formation of titanium carbide using titanium and carbon-nanotube powders by laser cladding (original) (raw)
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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.
Materials
This paper describes the microstructure and properties of titanium-based composites obtained as a result of a reactive spark plasma sintering of a mixture of titanium and nanostructured (Ti,Mo)C-type carbide in a carbon shell. Composites with different ceramic addition mass percentage (10 and 20 wt %) were produced. Effect of content of elemental carbon covering nc-(Ti,Mo)C reinforcing phase particles on the microstructure, mechanical, tribological, and corrosion properties of the titanium-based composites was investigated. The microstructural evolution, mechanical properties, and tribological behavior of the Ti + (Ti,Mo)C/C composites were evaluated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), electron backscatter diffraction analysis (EBSD), X-ray photoelectron spectroscopy (XPS), 3D confocal laser scanning microscopy, nanoindentation, and ball-on-disk wear test. Moreover, corrosion resistance in a 3.5 wt % NaCl sol...
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.
Microstructure and wear properties of Fe–TiC surface composite coating by laser cladding
Journal of Materials Science, 2008
AISI 1045 steel surface was alloyed with pre-placed ferrotitanium and graphite powders by using a 5-kW CO2 laser. In situ TiC particles reinforced Fe-based surface composite coating was fabricated. The microstructure 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 with cubic or flower-like dendritic form were synthesized via in situ reaction between ferrotitanium and graphite in the molten pool during laser cladding process. The TiC carbides were distributed uniformly in the composite coating. The TiC/matrix interface was found to be free from cracks and deleterious phase. The coatings reinforced by TiC particles revealed higher wear resistance than that of the substrate.
Purpose: of this paper is characterization and wear properties of carbon nanotubes incorporated ceramic coatings on Ti6Al4V and Ti6Al7Nb alloys. Design/methodology/approach: Carbon nanotubes (CNTs) incorporated ceramic coatings were fabricated by micro arc oxidation (MAO) method to improve the tribological performance of Ti6Al4V and Ti6Al7Nb alloys for wear resistant applications. Titania and CNTs incorporated titania coatings were formed on Ti6Al4V and Ti6Al7Nb alloys via MAO process. Surface and cross-sectional morphology, phase composition, thickness and roughness of the ceramic coatings were investigated by using scanning electron microscopy (SEM), X-ray diffraction (XRD) and surface profilometer. Findings: Wear behavior of bare titanium alloys and those of their oxidized surfaces (with and without CNTs addition) were evaluated by reciprocating wear test against 100Cr6 steel ball at dry sliding condition. XRD analyses of the oxidized samples demonstrated that coatings were consisted mainly of rutile and aluminum titanate. Surface morphologies of the coatings revealed that CNTs addition into the electrolyte led to generation of less porous, flat regions surrounded by relatively irregular-shaped pores on the surface of the coatings. Wear rate of CNTs incorporated coatings was decreased significantly compared to coatings generated without CNTs addition. Research limitations/implications: CNTs addition into the base electrolyte sharply decreases wear rate of both alloys, and there is no significant difference between the wear rates of Ti6Al4V and Ti6Al7Nb alloys oxidized in CNTs added electrolyte. Originality/value: Titanium and its alloys are attracting a great deal of attention especially in automotive and aerospace industries. However, titanium-based materials tend to have insufficient wear resistance in abrasive conditions. In an attempt to overcome this limitation, carbon nanotubes (CNTs) incorporated ceramic coatings were fabricated.
In this paper, Titanium alloy (Ti6Al4V) powder and boron carbide (B 4 C) powder metal matrix composites (MMCs) were embedded on titanium alloy (Ti6Al4V) substrate using laser metal deposition (LMD). The laser power was varied between 800 W and 2400 W at an interval of 200 W while all other processing parameters were kept constant. The maximum capacity of the laser system is 3.0 KW which provides beam size of 4 mm for the control characterization of the deposited samples. The microstructural properties of the deposited samples were profound with α and β (intermetallic phase of α+β) of titanium alloy and boron carbide particles. The optical microscope (OM) was employed to characterise the grain sizes and microstructures. The microhardness were characterized using the Vickers' hardness indenter in which the microhardness of the composites revealed an increase in the samples as the laser power increases. The hardness were observed to be between 371Hv and 471Hv for the cladded samples when compared to the substrate with approximately 360Hv.
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.
Microstructures and wear properties of laser cladding Co-based composite coatings on Ti–6Al–4V
Materials & Design, 2015
Metal matrix composite (MMC) coatings were fabricated on Ti-6Al-4V titanium alloy by laser cladding. Co42 self-fluxing powder, B 4 C, SiC and Y 2 O 3 were employed as the cladding materials. Microstructures and the wear properties of the different composite coatings were investigated comparatively. Results showed that the laser cladding coatings were mainly reinforced by CoTi, CoTi 2 , NiTi, TiC, TiB 2 , TiB, Cr 7 C 3 and Ti 5 Si 3. The micro-hardness of the cladding coatings were equivalent to 3-4 times the Ti-6Al-4V substrate. Laser cladding coating exhibiting outstanding wear resistance was fabricated with the addition of 20 wt.% B 4 C, 7 wt.% SiC and 1 wt.% Y 2 O 3. The wear resistance was enhanced by over 10 times compared with the substrate. However, with more SiC addition (14 wt.%), a higher micro-hardness was obtained together with poor wear resistance. The wear mechanism of the coatings was discussed by referring to the microstructures and the wear morphologies.
Micromechanical and Tribological Properties of Nanocomposite nc-TiC/a-C Coatings
Solid State Phenomena, 2011
The nanocomposite coatings composed of nanocrystalline TiC grains embedded in hydrogen free amorphous carbon a-C matrix (nc-TiC/a-C) were deposited by magnetron sputtering on the two substrates, oxygen hardened Ti-6Al-4V alloy and heat treated VANADIS 23 steel. The Ti-6Al-4V alloy was oxygen hardened by plasma glow discharge. Micro-mechanical and tribological properties as well as coating adhesion to the substrates were investigated. Micro/nanostructure of the coatings and the substrates were examined using scanning- and transmission electron microscopy methods as well as X-ray diffractometry. Nano-, microhardness tests performed for the coated materials showed average hardness 13.4-14.7 GPa and modulus of elasticity 160 GPa. Scratch test revealed good adhesion of coatings to the both substrates. The nanocomposite coatings significantly improved tribological properties of the titanium alloy and steel, increased wear resistance and decreased friction coefficient.
Microstructure and surface properties of laser-remelted titanium nitride coatings on titanium
Surface and Coatings Technology, 2005
Laser remelted tracks were produced on the surface of titanium nitride (TiN) coated titanium. In order to produce different microstructures, seven conditions were tested by varying laser power and speed. The remelted tracks were then evaluated from the surface mechanics point of view through microhardness and sliding friction tests. Samples produced in conditions where laser speed varied from 5 to 100 mm/s presented high TiN surface content and increased hardness. In the velocity range of 20-100 mm/s, the remelted tracks presented high resistance to wear. The dendrites tend to coalescence when the scanning velocity is below 2 mm/s. The low velocity experiments (1 and 2 mm/s) presented eutectoid decomposition of the TiN/Ti phases creating a Ti 2 N phase at boundaries, which decreased the hardness and the wear resistance at surface. The results indicated that the best condition in terms of surface properties is obtained when the scanning rate is 5 mm/s and the laser power is 500 W. D