Ti-coated Diamond Particles Research Articles

Reaction mechanisms for Ti coatings on diamond

Efficient interface management between diamond and metal is crucial for achieving optimal performance in metal-matrix/diamond composites. Here, the Ti coatings prepared at various pressures were deposited on diamond particles by DC magnetron sputtering. The microstructure and bonding strength of the resulting coatings were systematically investigated. The results showed that the microstructure of the Ti coatings depended on the deposition pressure. All coating surfaces had a granular morphology, and the augment of deposition pressure was favorable for refining the coatings' grains. The Ti coating prepared at 1.0 Pa was fine and uniform with no obvious defects, displaying the optimal deposition quality and bonding strength. Furthermore, it was found that the annealing temperature played a key role in the reaction between the Ti coating and the diamond. The TiC phase in the Ti-coated diamond particles exhibited a progressive increase with rising temperature, and the Ti-coated diamond underwent completely transformation into TiC-coated diamond at 1000 °C. The experimental results and molecular dynamics simulation revealed that the Ti coating reacted more violently with the diamond-(100) facet than it did with the diamond-(111) facet at high temperature. This work provided a new solution for interface management strategy of high-quality metal-matrix/diamond composites.

Effects of the In Situ Growth of CNTs on Ti-Coated Diamond Surfaces on the Mechanical Properties of Diamond/Aluminum Composites.

Diamond/aluminum composites have attracted significant attention as novel thermal management materials, with their interfacial bonding state and configuration playing a crucial role in determining their thermal conductivity and mechanical properties. The present work aims to evaluate the bending strength and thermal conductivity of CNT-modified Ti-coated diamond/aluminum composites with multi-scale structures. The Fe catalyst was encapsulated on the surface of Ti-coated diamond particles using the solution impregnation method, and CNTs were grown in situ on the surface of Ti-coated diamond particles using the plasma-enhanced chemical vapor deposition (PECVD) method. We investigated the influence of interface structure on the thermal conductivity and mechanical properties of diamond/aluminum composites. The results show that the CNT-modified Ti-coated diamond/aluminum composite exhibits excellent bending strength, reaching up to 281 MPa, compared to uncoated diamond/aluminum composites and Ti-coated diamond/aluminum composites. The selective bonding between diamond and aluminum was improved by the interfacial reaction between Ti and diamond particles, as well as between CNT and Al. This led to the enhanced mechanical properties of Ti-coated diamond/aluminum composites while maintaining acceptable thermal conductivity. This work provides insights into the interface's configuration design and the performance optimization of diamond/metal composites for thermal management.

Improved Bending Strength and Thermal Conductivity of Diamond/Al Composites with Ti Coating Fabricated by Liquid-Solid Separation Method.

In response to the rapid development of high-performance electronic devices, diamond/Al composites with high thermal conductivity (TC) have been considered as the latest generation of thermal management materials. This study involved the fabrication of diamond/Al composites reinforced with Ti-coated diamond particles using a liquid-solid separation (LSS) method. The interfacial characteristics of composites both without and with Ti coatings were evaluated using SEM, XRD, and EMPA. The results show that the LSS technology can fabricate diamond/Al composites without Al4C3, hence guaranteeing excellent mechanical and thermophysical properties. The higher TC of the diamond/Al composite with a Ti coating was attributed to the favorable metallurgical bonding interface compounds. Due to the non-wettability between diamond and Al, the TC of uncoated diamond particle-reinforced composites was only 149 W/m·K. The TC of Ti-coated composites increased by 85.9% to 277 W/m·K. A simultaneous comparison and analysis were performed on the features of composites reinforced by Ti and Cr coatings. The results suggest that the application of the Ti coating increases the bending strength of the composite, while the Cr coating enhances the TC of the composite. We calculate the theoretical TC of the diamond/Al composite by using the differential effective medium (DEM) and Maxwell prediction model and analyze the effect of Ti coating on the TC of the composite.

Improvement in effectiveness of diamond in strengthening the porous aluminium composite

In this study, an aluminum (Al) alloy matrix reinforced with uncoated and titanium (Ti) -coated diamond were developed using powder metallurgy technique where polymethylmethacrylate (PMMA) particles were employed as space holders. The weight % of uncoated and coated diamond varied as (0, 6, 9, 12, 15, and 20 wt.%). Microstructural and elemental analysis was examined using scanning electron microscopy and energy dispersive spectroscope, respectively. The relative density and porosity that were in the range of 0.72–0.92 and 31–44% respectively, were measured using Archimedes principle. The compressive properties were measured and correlated with microstructure observations. The microstructure of the composite samples revealed presence of well-defined macro pores with good interfacial integrity. The X-ray diffraction revealed the presence of strengthening phases such as Al2Ti, Mg2Sn, AlB12, Cu5Sn6, Al12Mg17 and MgB2 phases formed as a result of addition of metal additives in Al matrix. Further improvement in the strength was obtained by using Ti-coated diamond particles as reinforcement. As Ti formed a good interface between the Al alloy matrix and the diamond thereby preventing the formation of undesirable carbide phases. There was an improvement in plateau stress and energy absorption capacity of 82 and 88% as compared to unreinforced porous sample. The maximum values obtained for the plateau stress and energy absorption capacity were 45.12 MPa and 13.68 MJ/m3 respectively for 9 wt.% of Ti-coated diamond reinforced composites. Uncoated diamond reinforced composites, on the other hand, reduced the strength of porous Al alloy matrix due to the formation of brittle intermetallic compound such as carbides (Al2C3) at the interface. As a result, the coated diamond particle surface modifies and improves the wettability of the Al alloy matrix and diamond interface.

Preparation of diamond/aluminum composite with titanium coating on diamond powder by microwave technology

In this research, the diamond particles were coated with titanium by microwave heating method, then the Ti-coated diamond particles were used as raw material to fabricate the diamond/Al composites by microwave sintering. The result shows that the diamond particles could be covered with a uniform and continuous Ti coating under microwave irradiation, and the best Ti coating was obtained at 810 °C for 1 h. The metallic bond between diamond and Ti was formed to generate the intermediate transition layer of TiC. The diamond/Al composites which used Ti-coated diamond particles as raw material and were fabricated by microwave sintering show high relative density and hardness. The relative density and hardness of the diamond/Al composites increased with the temperature. While the composites were sintered at 710 °C for 1 h, the density could reach 2.855 g·cm−3, and relative density was 92.09%, which shows better microstructures and properties. There is Al3Ti alloy phase in Ti-coated diamond/Al composites, so the Ti-coated diamond can be well combined with the Al matrix, which can further improve the properties of the composites.

Interface manipulation and its effects on the resultant thermal conductivity of hot-forged copper/Ti-coated diamond composites

Copper/55 vol%Ti-coated diamond composites are successfully fabricated by hot forging from pure copper powder and Ti-coated diamond particles, and the interphase layer structure of the composites are influenced by the pre-annealing Ti-coated diamond particles. It shows that the diamond particles start to react with the Ti coating to form TiC phase at 800 °C, and the reaction is activated first on the diamond-{111} facets, attributed to the sp3 -hybridized crystal structure transforming into relatively disordered and highly active sp2 -hybridized crystal structure (graphite cluster), and this leads to anisotropy structures are formed between the diamond-{100} and -{111} facets for the 800 °C-annealed Ti-coated diamond particles. With increasing the annealing temperature to 900 °C and 1050 °C, diamond-{100} become more active and there are more nucleation sites to form TiC particles due to the formation of the diamond-{111} facet on the diamond-{100} surface and the carbon atoms are easier to be freed on the diamond-{100} compared to diamond-{111}, and the microstructural difference between diamond-{100} and -{111} facets are significantly reduced. In-situ formation of TiC particles during hot forging process enables to form strong interface bond between the diamond and the copper matrix for Ti-800 °C-Cu/Dia, attributed to the diamond has high TiC interface coverage rate (about 79.5%), intact contact interface between the diamond and the copper, and rough surface of the formed interphase layer. These lead to the Ti-800 °C-Cu/Dia has the highest thermal conductivity (about 350 W/(mK)) among the three fabricated copper/diamond composites. This research provides insight on copper/diamond composite’s interface formation mechanisms and manipulation for regulating the thermal conductivity property.

The Impact of Interface Characteristics on Mechanical Performance of a Hot-Forged Cu/Ti-Coated-Diamond Composite

The Cu/55vol.%diamond (Ti) composites were fabricated by hot forging of the cold-pressed powder preforms, consisted of elemental copper powders and Ti-coated diamond particles, at 800 °C (800C-Cu/55Dia composite) and 1050 °C (1050C-Cu55Dia composite), respectively. Well bonded interface was achieved between the diamond and the copper matrix for the 800C-Cu/55Dia composite, and the coverage of diamond by interface was about 96%, attributed to homogeneously distributed nanospherical TiC interface formed on the diamond surface. However, obvious coarse TiC particle size and spallation of the formed interface were observed in the 1050C-Cu55Dia composite, implying that the composite had a relatively low bonding strength. The formed chemical bonding, good wettability and strong mechanical interlocking between the diamond and the copper matrix enable the 800C-Cu/55Dia composite having a high tensile strength of 145 MPa and a strain at fracture of 0.35%, which are about 260% and 170% higher than those of the 1050C-Cu55Dia composite, suggesting that the 800C-Cu/55Dia composite has the potential to have a high thermal conductivity and use as high-performance heat sink materials.

High thermal conductivity and strong interface bonding of a hot-forged Cu/Ti-coated-diamond composite

Cu/55 vol%diamond (Ti) composites are prepared by hot forging of cold-pressed powder preforms, consisted of pure Cu powders and 50 nm-thick Ti-coated diamond particles, at 800 °C (800-Cu/55Dia) and 1050 °C (1050-Cu/55Dia), respectively. It finds that the TiC coverage of diamond surface is 96% in 800-Cu/55Dia and 70% in 1050-Cu/55Dia. Nano-spherical TiC particles are homogeneously dispersed on diamond surface to form a rough surface for 800-Cu/55Dia. This leads to a strong interface bonding is formed in 800-Cu/55Dia, having a flexural strength of 418 MPa. Sever interfacial layer spallation, smooth and flat surface of interfacial layer make 1050-Cu/55Dia have a relatively low interface bonding. The high coverage of diamond by interfacial layer, formation of dispersed nano-spherical TiC particles, and strong interface bonding enables the thermal conductivity (TC) of 800-Cu/55Dia is as high as 550 W/mK (99% of the theoretical value), and a CTE of 7 × 10−6/K at 313 K. The fabricated copper/diamond composite has better mechanical and thermophysical properties than the most reported copper/diamond (the diamond particle size is < 100 μm) composites, demonstrating that powder hot-forging technique we developed is a cost-effective process and feasible to produce a copper/diamond composite with high mechanical and thermophysical performance for high-power thermal management applications.

Vacuum tribological properties and impact toughness of polycrystalline diamond based on titanium-coated diamond particle

In this work, the diamond particles were deposited with titanium (Ti) by the magnetron sputtering, and the polycrystalline diamond compact synthesized by the Ti-coated diamond particles (Ti-PDC) was prepared by high temperature and high pressure (HTHP) sintering method. The scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) results show that the Ti coating uniformly distributes on the surface of diamond particles. The results of X-ray diffraction (XRD) indicate that the TiC phase has been produced during the sintering process. The impact toughness of the Ti-PDC is higher than that of the pristine polycrystalline diamond compact (P-PDC). In addition, the friction coefficients of Ti-PDC under different vacuum conditions reveal lower values than those of the P-PDC. A less number of exfoliated pits can be observed on the worn Ti-PDC surface. The improved impact toughness and vacuum friction performance of Ti-PDC may be attributed to the enhanced bonding strength between diamond particles, which is induced by the TiC phase. In brief, the Ti-coated diamond particles can improve the bonding strength between diamond grains and thus yield to an enhanced service performance of the PDC.

Enhanced thermal conductivity in Cu/diamond composites by tailoring the thickness of interfacial TiC layer

Diamond particles reinforced Cu matrix (Cu/diamond) composites were fabricated by gas pressure infiltration using Ti-coated diamond particles with Ti coating from 65 nm to 850 nm. The scanning transmission electron microscopy (STEM) characterizes that the Ti coating transforms from elemental Ti to TiC after infiltration, and the crystallographic orientation relationship between diamond and TiC is [1 1 0]diamond//[1 1 0]TiC and (1 1 1)diamond//(1 1 1)TiC. The thermal conductivity of the Cu/Ti-diamond composites firstly increases and then decreases with increasing Ti coating thickness, giving a maximal value of 811 W m−1 K−1 at 220 nm Ti-coating layer. The results clearly manifest the effect of interfacial layer thickness on the thermal conductivity of Cu/diamond composites.

Preparation of Ti-coated diamond particles by microwave heating

Depositing strong carbide-forming elements on diamond surface can dramatically improve the interfacial bonding strength between diamond grits and metal matrix. In the present work, investigation on the preparation of Ti-coated diamond particles by microwave heating has been conducted. The morphology, microstructure, and the chemical composition of Ti-coated diamond particles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive x-ray spectrometer (EDX). The thickness of Ti coating was measured and the interfacial binding strength between Ti coating and diamond was analyzed. The results show that the surface of the diamond particles could be successfully coated with Ti, forming a uniform and continuous Ti-coated layer. The TiC was found to form between the surface of diamond particles and Ti-coated layer. The amount of TiC as well as the thickness of coating increased with increasing coating temperature, furthermore, the grain size of the coating also grew gradually. The interfacial bonding strength between coating and diamond was found to be best at the temperature of 760°C.

Interface characterization of a Cu–Ti-coated diamond system

Diamond particles dispersed metal matrix composites such as Cu/diamond composites are desirable packaging materials for microelectronic devices because of their potentially high thermal conductivity. The thermal resistance at the metal/diamond interface, however, hinders the development and application of the composites. A Ti coating on diamond particles is proved to enhance the thermal conductivity of Cu/diamond composites. So far the interfaces between diamond particle and Ti layer as well as between Ti layer and Cu matrix have not been clearly identified. This paper aims to study the microstructure of the two interfaces via a Cu–Ti-coated diamond system. Synthetic single-crystalline diamond particles were firstly coated with metallic Ti by using a molten-salt method, and then magnetron sputtering was used to deposit a Cu layer onto the Ti-coated diamond particles. The Cu–Ti-coated diamond particles were heated at 1073K for 30min in vacuum to simulate the actual processing of the Cu/diamond composites. Auger electron spectroscopy (AES) results show that TiC is formed between the diamond particle and the Ti layer. Between Ti and Cu layers, Cu was found to diffuse into the Ti layer and to create a compound phase at the Ti/Cu interface. The finding provides an experimental basis for the interface design and production of the Cu/diamond composites.

Microstructure and thermal conductivity of Cu/diamond composites with Ti-coated diamond particles produced by gas pressure infiltration

As an attractive thermal management material, diamond particles reinforced Cu matrix (Cu/diamond) composites generally exhibit thermal conductivities lower than expected. To exploit the potential of heat conduction, a combination of Ti coating on diamond particles and gas pressure infiltration was used to prepare Cu/diamond(Ti) composites. A high thermal conductivity of 716 W/mK and a low coefficient of thermal expansion of 5.8 ppm/K at 323 K were obtained in the composites. Auger electron spectroscopy (AES) characterization shows that a TiC layer was formed between Cu matrix and diamond reinforcement, which is responsible for the enhancement of thermal conductivity. The results suggest that Ti coating can significantly promote interface bonding between Cu and diamond and gas pressure infiltration is an effective method to produce Cu/diamond composites.

Mechanical properties of diamond/Al composites with Ti-coated diamond particles produced by gas-assisted pressure infiltration

Diamond particles reinforced Al matrix (diamond/Al) composites were produced by a gas-assisted pressure infiltration method. Ti coating on diamond particles was carried out to bring interfacial TiC layer between diamond reinforcements and Al matrix. The TiC layer was found to play a critical role in enhancing mechanical properties of the composites, owing to strong connection between dissimilar phases. Three analytical models of Mori–Tanaka, generalized self-consistent, and Torquato identical hard spheres were used to correlate the monotonic uniaxial stress–strain curves of the diamond/Al composites. The results suggest that Ti coating on diamond particles is a feasible way to strengthening diamond/Al composites.

The role of Ti coating in enhancing tensile strength of Al/diamond composites

Aluminum matrix composites reinforced with Ti-coated diamond particles (Al/Ti-diamond composites) were produced by squeeze casting. The plating time of molten-salt was varied to investigate the effects on the phase structure and thickness of Ti coating on diamond particles. The highest tensile strength of 76MPa was obtained for the composite with 90min plating time. In this composite, a reasonable thickness of TiC layer was found to tightly connect Al matrix with diamond reinforcements. The tensile strength decreased when the plating time is longer than 90min, owing to weak interfacial bonding between additionally formed Ti layer and Al matrix. The results show that appropriate selection of Ti coating can effectively improve interfacial bonding and tensile strength of Al/diamond composites.

Enhanced thermal conductivity in copper matrix composites reinforced with titanium-coated diamond particles

Cu matrix composites reinforced with Ti-coated diamond particles were consolidated by spark plasma sintering . A layered structure of TiC/transition layer was formed uniformly on the diamond particle surface, with a total thickness of ∼285 nm. A high thermal conductivity of 493 W m −1 K −1 was achieved in the Cu/Ti-coated diamond composites. The greatly enhanced thermal conductivity is ascribed to the 285 nm thick Ti coating. Ti coating on diamond particles is therefore an effective way to enhance the thermal conductivity of Cu/diamond composites.

Thermal conductivity and microstructure of Al/diamond composites with Ti-coated diamond particles consolidated by spark plasma sintering

Metal/diamond composites have been considered as the new generation of thermal management material. The critical challenge to obtain composites with high thermal conductivity (TC) is to improve the interfacial bonding between the matrix and diamond. In the present study, a titanium coating was plated on the surface of diamond particles via vacuum evaporation–deposition, and Al/diamond composites were consolidated by spark plasma sintering (SPS) technique. The TC and microstructure of composites, respectively, with coated and uncoated diamond particles are compared and discussed. The results show that the Ti coating can significantly increase the wetting property between Al and diamond, leading to a strong interfacial bonding. The diffusion of Ti into the matrix and the formation of TiC are detected at the Al–diamond interface. The properties of composites, respectively, with coated and uncoated diamond exhibit different trends with increasing sintering temperature or diamond volume fraction. Compared with composites with uncoated particles, the Al/Ti–diamond composites obtained the much higher relative density and TC as high as 491 W/mK. Based on the comparison between the experimental and theoretical values, it is found that the thermal conductivities of Al/Ti–diamond composites have reached or surpassed the theoretical calculations with the particle volume fraction not more than 50%.

Microstructure and thermal expansion of Ti coated diamond/Al composites

A titanium coating fabricated via vacuum vapor deposition for diamond/Al composites was used to improve the interfacial bonding strength between diamond particles and Al matrix, and the Ti coated diamond particles reinforced Al matrix composites were prepared by gas pressure infiltration for electronic packaging. The surface structure of the Ti coated diamond particles was investigated by XRD and SEM. The interfacial characteristics and fracture surfaces were observed by SEM and EDS. The coefficient of thermal expansion(CTE) of 50% (volume fraction) Ti coated diamond particles reinforced Al matrix composites was measured. The Ti coating on diamond before infiltration consists of inner TiC layer and outer TiO 2 layer, and the inner TiC layer is very stable and cannot be removed during infiltration process. Fractographs of the composites illustrate that aluminum matrix fracture is the dominant fracture mechanism, and the stepped breakage of a diamond particle indicates strong interfacial bonding between the Ti coated diamond particles and the Al matrix. The measured low CTEs (5.07×10 −6−9.27×10 −6K −1) of the composites also show the strong interfacial bonding between the Ti coated diamond particles and the Al matrix.

Pulsed laser deposition of metallic films on the surface of diamond particles for diamond saw blades

Ti or Ni films have been deposited on the diamond particle surfaces by pulsed laser deposition. Compressive resistance of the uncoated and coated diamond particles was measured, respectively, in the experiments. The compressive resistance of the Ti-coated diamonds particles was found much higher than that of the uncoated ones. It increased by 39%. The surface morphology is observed by the metallography microscope. The surface of the uncoated diamonds particles had many hollows and flaws, while the surface of Ni-coated diamond particles was flat and smooth, and the surface of Ti-coated diamond particles had some metal masses that stood out of the surface of the Ti-coated film. The components of the metallic films of diamond particles were examined by X-ray diffractometry (XRD). TiC was found formed on the Ti-coated diamond surface, which resulted in increased surface bonding strength between the diamond particles and the Ti films. Meanwhile, TiC also favored improving the bonding strength between the coated diamond particles and the binding materials. Moreover, the bending resistance of the diamond saw blade made of Ti-coated diamond was drastically higher than that of other diamond saw blades, which also played an important role in improving the blade's cutting ability and lifetime. Therefore, it was most appropriate that the diamond saw blade was made of Ti-coated diamond particles rather than other materials.