High-temperature Synthesis Casting Research Articles

Effect of Ar Gas Pressure on Phase Separation of Tungsten Silicides Intermetallic Compound <i><i>In Situ</i></i> Self-Propagating High Temperature Synthesis-Casting Process

Tungsten silicides intermetallic compound (WSi2) was synthesized in-situ by self-propagating high temperature synthesis-casting of WO3-Si-Al system in Ar gas environment. It is proposed that the extent of phase separation between oxide ceramic and intermetallic compound depends on the reaction temperature that made a lower viscosity and longer lifetime of the melted. The effects of inert gas pressure on densification of the intemetallic product were investigated.

Tribological performances of Ni3Si–Cr7C3 composite coatings under water and acid environments

The Ni3Si–Cr7C3 composite coatings with various contents of Cr7C3 were deposited on the AISI 1020 steel substrate by self-propagating high temperature synthesis casting and their tribological performances were studied under water and acid environments. The results demonstrated that all the Ni3Si–Cr7C3 composite coatings showed excellent friction-reduction, and wear resistance performances compared to the substrate and the AISI 321 stainless steel. While it is worth noting that the coating containing 37.2wt.% of Cr7C3 exhibited the best tribological performances. In addition, the friction reduction and wear resistant mechanism was also discussed and considered to be microploughing under both water and acid environments.

A study of Ni 3Si-based composite coating fabricated by self-propagating high temperature synthesis casting route

A Ni 3Si–Cr 7C 3 composite coating was fabricated on AISI 1020 steel substrate by self-propagating high-temperature synthesis (SHS) casting route. Phase composition, microhardness and dry sliding wear behavior of the coating were studied. The results indicated that the coating was mainly consisted of Ni 3Si and Cr 7C 3. The microhardness of coating is about 900 HV. The friction and wear tests showed that although the friction coefficient had no obvious change, the wear resistance of the AISI 1020 steel matrix was improved greatly. Also, the corrosion test result showed that the coating had an excellent corrosion resistance.

Large-scale Fe–C nanoeutectic alloy prepared by a self-propagating high-temperature synthesis casting route

It is a challenge to prepare large-scale bulk nanostructured materials by simple and low-cost processing. Large-scale bulk nanostructured Fe 1.87 C 0.13 (Fe–6.5 at.% C) material with 80–100 nm lamellar eutectic and dimensions of 100 mm (diameter) × 8 mm has been successfully synthesized by a simple and inexpensive self-propagating high-temperature synthesis casting route. The nanostructured Fe 1.87 C 0.13 material exhibits high yield strength (1300 MPa) and good ductility (∼40%) in compressive testing. The mechanism of nanostructure formation is discussed.

Fabrication of bulk Al 2O 3 dispersed ultrafine-grained Cu matrix composite by self-propagating high-temperature synthesis casting route

Bulk Al 2O 3 dispersed ultrafine-grained (UFG) Cu matrix composite has been fabricated by self-propagating high-temperature synthesis (SHS) casting route. The microstructures and mechanical properties of the as-fabricated materials have been investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis, and microhardness measurements and compression tests, respectively. The results show that the as-fabricated material has small amount of entrapped Al 2O 3 particles in uniform microstructure Cu having a grain size ranging from 200–500 nm with an elevated compressive yield stress (298 MPa) and an improved microhardness value (1.06 GPa). The possible strengthening mechanism of the product has been discussed.

Microstructure and properties of Ni3Si alloyed with Cr fabricated by self-propagating high-temperature synthesis casting route

Ni3Si alloys with 20, 30, and 40 wt pct Cr were fabricated by self-propagating high-temperature synthesis casting at 543 K. Thermite reaction (Cr2O3+5CrO3+12Al=7Cr+6Al2O3) was used in Cr alloying. The method is simple and economical when used to prepare Ni3Si-based alloys. The process is described in detail. The alloys were analyzed with X-ray diffraction (XRD) and scanning electron microscopy (SEM) with X-ray energy dispersive spectroscopy (EDS). The results showed the alloys mainly consisted of Ni3Si and Ni5Si2 with dissolved Cr and Cr phases. Phases and microstructures of the alloys varied with Cr content. Microhardness, bending and compressive strength, and wear rate of the alloys were measured. Microhardness of the alloys was higher than that of Ni3Si without Cr and increased with Cr content. Bending and compressive strength of the alloys were better than those of the Ni3Si without Cr, and those of the alloy with 30 wt pct Cr were the highest. The wear rate of the alloys was lower than that of the Ni3Si without Cr and decreased with Cr content.

Microstructure and properties of Fe3Al–Fe3AlC0.5 composites prepared by self-propagating high temperature synthesis casting

Abstract Fe 3 Al composite materials with 40, 60 and 80 wt.% Fe 3 AlC 0.5 were fabricated by self-propagating high temperature synthesis (SHS) casting processing and analyzed with X-ray diffraction (XRD) and scanning electron microscopy (SEM). Microhardness, bending strength and wear rate of the composites were measured. The materials mainly consisted of Fe 3 Al and Fe 3 AlC 0.5 phases. The adherence of the reinforcement and the matrix was good. There were no cracks at the interface of the phases in the materials. Hardness of the composites increased with Fe 3 AlC 0.5 fraction. Bending strength of the composites was high and that of the composite with 60 wt.% Fe 3 AlC 0.5 was the highest. Wear rates of the composites were low and those of the composites with 60 and 80 wt.% Fe 3 AlC 0.5 were lower than that of the composite with 40 wt.% Fe 3 AlC 0.5 .

Study of wear resistant MoSi 2–SiC composites fabricated by self-propagating high temperature synthesis casting

MoSi 2 composites with 10, 15 and 20 wt.% SiC were fabricated as wear resistant materials by self-propagating high temperature synthesis (SHS) casting route. The composites were analyzed with X-ray diffraction (XRD) and scanning electron microscopy (SEM) with X-ray energy dispersive spectroscopy (EDS). Hardness, toughness and wear rate of the composites were measured. XRD examination showed that the composites mainly consisted of MoSi 2, SiC and Al 2O 3 phases. Content of Al 2O 3 was about 3 wt.% in the composites. Microstructures of the composites varied with the amount of SiC. Silicon carbide phase presented in the composites was in the term of large particles or short fibers depending on the amount of SiC presented in the composites. Cracks existed near interfaces of the large SiC particles and MoSi 2 matrix in composites with 10 and 15 wt.% SiC whereas they did not appear in composite with 20 wt.% SiC. Hardness and toughness of the composites increased with increase of SiC. Wear rate of the composites and its sensitivity to load dramatically decreased with SiC. Composite with 20 wt.% SiC had the best properties.

Study of Ni3Al-Cr7C3 composite materials fabricated by self-propagating high-temperature synthesis casting route

Ni3Al composite materials with 15, 25, and 50 wt pct Cr7C3 were fabricated by self-propagating high-temperature synthesis (SHS) casting route and analyzed with X-ray diffraction (XRD) and scanning electron microscopy (SEM) with X-ray energy dispersive spectroscopy (EDS). Microhardness and wear property of the materials were measured. The results showed that the materials mainly consisted of Ni3Al and Cr7C3 phases and were dense and pure. The Cr7C3 phase was uniformly distributed in the Ni3Al matrix and the adherence of the reinforcement and the matrix was strong. Phases and microstructure of the materials varied with Cr7C3 content. There were no cracks in the materials with 15 and 25 wt pct Cr7C3, whereas cracks appeared in the material with 50 wt pct Cr7C3. Microhardness of the materials was much higher than that of pure Ni3Al material and increased with Cr7C3 content. Wear resistance of the materials was much higher than that of pure Ni3Al material and the material with 25 wt pct Cr7C3 had the best wear resistance.

Study of Ni3 Al–Cr7 C3 coating fabricated by self-propagating high temperature synthesis casting route

A coating on carbon steel was fabricated by a self-propagating high temperature synthesis (SHS) casting route. The process is described in detail. The phases in the coating were examined using X-ray diffraction (XRD). The microstructures of the coating and the substrate were analysed using electron probe microanalysis (EPMA) and optical microscopy, respectively. The wear behaviour and microhardness of the coating were determined. The experimental results show that the coating was composed of Ni3 Al and Cr7 C3 phases and had a dense microstructure. Metallurgical bonding had formed between the coating and the substrate. The grain size of the substrate near the interface was coarsened. The wear resistance of the coating is better than that of a bearing steel or a Ni3 Al coating. The microhardness of the coating is higher than that of a Ni3 Al coating or the substrate.