Addition Of SiCp Research Articles

Synthesis and characterization of 7075 Al alloy–SiC composites

PurposeMechanical properties are highly sensitive to the microstructure, and these are indirectly related to solidification parameters and processing conditions. AA7075 possesses lightweight and excellent properties as structural material which can be optimized with SiCp addition and a good fabrication technique.Design/methodology/approach7000 series aluminium alloys exhibit the highest mechanical properties. They are used for high-strength structural applications such as aircraft parts and sporting goods. The desirable properties of these alloys are: low density, high stiffness, specific strength, good wear resistance and creep resistance. The focus of this work is to investigate the microstructure of composites formed by the dispersion of silicon carbide particles (SiC) into AA7075 by stir casting processes. 7075 Al alloy is reinforced with 10 and 15 wt.% SiCp of size 10–20 µm by stir casting process. The composites have been characterized by X-ray diffraction and scanning electron microscopy, differential thermal analysis and electron probe microscopic analysis.FindingsSiCp distribution and interaction with AA7075 matrix have been studied. AA7075/10 wt.%/SiCp (10–20 µm) and AA7075/15 wt.%/SiCp (10–20 µm) composites microstructure showed excellent SiCp distribution into AA7075 matrix. In addition, no evidence of secondary chemical reactions has been observed in X-ray diffraction and electron probe microscopic analysis.Originality/valueLittle experimental work has been reported so far about effect of addition of 10 and 15 wt.% SiCp of size (10–20 µm) on the microstructure of 7075 Al alloy fabricated by stir casting process. The present investigation has been carried out to study the microstructure and carry out XRD, DTA and EPMA analysis of 7075 Al alloy, 10 and 15 wt.% SiCp of size (10–20 µm) composite and detect the interfacial reactions with the objective to minimize the formation of Al4C3.

High-temperature oxidation resistance of a Ti–Al–Sn–Zr titanium matrix composites reinforced with in situ TiC and Ti5Si3 fabricated by powder metallurgy

A mixture of the Ti–Al–Sn–Zr matrix powder and SiC particles was used as a raw powder to fabricate an in situ TiC and Ti5Si3 reinforced titanium matrix composites (TMCs) via low energy ball milling–cold press forming–argon-protected sintering. The effects of various content of SiCp on the microstructure, phase composition and high-temperature oxidation behavior of the composites at 750 °C and 850 °C were studied. XRD results show that the oxidation phases were mainly composed of TiO2, Al2O3, SiO2 and α-Ti. According to the SEM images, the cross-sectional morphology of oxidation at 750 °C for 100 h shows that the oxide layer (20.00 μm) in the TMCs with 10.0 vol% SiCp after oxidation was denser and thinner and was 82.13% thinner than that of the matrix (98.00 μm). The parabolic rate constant (kp) of the oxidized composites decreases with the increase of SiCp content at 750 °C and 850 °C. In particular, the composites with 10 vol% SiCp content have smaller kp. All the results show that the addition of SiCp in TMCs can improve high-temperature oxidation resistance.

Rheo-Die-Casting of Al-Si-Mg Alloy and Al-Si-Mg/ SiCp Composites: Microstructure and Wear Behavior

Abstract In this paper, Rheo-Die Cast (RDC) Al-Si alloy with 7.5 wt % Si and 0.3 wt %Mg and Metal Matrix Composites (MMC’s) of RDC Al-Si composites with 5 to 20 vol. % of SiCp were produced by an in-house fabricated RDC machine. Microstructure and wear behavior of both RDC alloy and composites were investigated. Results indicated that the RDC samples have significantly refined microstructure with fine and uniform non-dendritic grains resulting increased hardness and enhanced wear resistance. Wear resistance is three times higher for sample with 20% SiCp than those without SiCp additions. Surfaces of wear test samples were investigated by SEM to study the effect of both grain structure and SiCp particulates on the wear mechanism. It was also observed that reinforced RDC samples showed improved hardness and wear resistance due to the presence of SiCp in the matrix of non-dendritic grains, obtained without modification treatment.

Abrasive wear behavior of SiC particulate reinforced AA5052 metal matrix composite

In the present work particulate reinforced aluminium metal matrix composites were developed by stir casting processing route in which AA5052 was reinforced with 5 wt% SiC-p of 63 µm particles size. The abrasive wear behavior of SiC-p reinforced AA5052 MMC was investigated and compared with that of unreinforced AA5052. The worn surfaces were analysed by optical microscopy. The results show that at all applied loading conditions, SiC-p reinforced AA5052 MMC gives improved tribological properties as compared to the unreinforced AA5052; but the addition of SiC-p increases the density of the AA5052.

Ultralight porous SiC with attracting strength: Freeze casting of polycarbosilane/SiCp/camphene-based suspensions

Porous SiC with highly oriented dendritic pore structure was prepared via freeze casting of the polycarbosilane/SiC powders (SiCp)/camphene-based suspensions. By varying the contents of SiCp addition and freeze casting parameters, porous SiC displayed a rather low density of 0.38–0.59 g/cm3, high porosity of 80.1–91%, pore size of 10.8–24.7 μm and excellent compressive and flexural strength ranging from 5.6 to 15.8 MPa and 3.7 to 11.3 MPa, respectively. A faster cooling rate resulted in porous SiC with smaller pore size and higher strength, while a higher SiCp/PCS mass ratio greatly decreased the linear shrinkage, and slightly decreased the porosity and pore size. With the addition of SiCp, porous SiC exhibited improved strength, decreased liner shrinkage and ultra-high porosity. The addition of submicron SiC particles enables the preparation of porous polymer-derived ceramics (PDCs) with controllable microstructure and porosity via freeze casting, which sheds light on ceramics with high porosity, low shrinkage, low density and satisfactory mechanical properties.

Understanding the anti-wear mechanism of SiCp/WE43 magnesium matrix composite

A detailed electron microscopy study was performed to investigate the wear mechanism of SiCp/WE43 magnesium matrix composite. The non-reinforced WE43 matrix alloy underwent serious plastic deformation during the sliding wear. The accumulated straining induced the formation of brittle delaminating tribolayer resulting in high wear rate of 4.73 ± 0.05 × 10−3 mm3 N−1 · m−1 and unstable friction coefficient of 0.49–0.88. Addition of SiCp into matrix alloy greatly improved its bearing capacity and wear performance. The hard SiCp effectively inhibited the fatigue crack propagation and suppressed the formation of brittle delaminating tribolayer. Lowering friction coefficient of ~0.38 and wear rate of 0.89 ± 0.07 × 10−3 mm3 N−1 · m−1 were found in the SiCp/WE43 composite. These current findings provided a comprehensive understanding for the anti-wear mechanism of SiCp reinforced magnesium matrix composite.

Microstructure and properties of Ti-Al-Sn-Zr-Nb-Si matrix composite reinforced with in-situ TiC and Ti5Si3 prepared by powder metallurgy

In this experiment, the Ti-Al-Sn-Zr-Nb-Si matrix composites reinforced with in situ TiC and Ti5Si3 were successfully prepared via low-energy ball mill—cold pressure—argon gas protection sintering. The effects of different contents of SiCp (3.5 vol%, 7 vol%, and 10 vol%) on the microstructure and properties of the composites were studied. The experimental results show that the surface of the composites exhibits a network structure due to the deposition of the Ti solid solution and the reinforcing phase at the grain boundary. The metallographic microstructure of the as-sintered composites indicates that the addition of SiCp in the composite material can refine the grain, and the grain size of the composite decreases with the increase of SiCp content. In addition, the microhardness of the composites is significantly enhanced with the increase of SiCp content. However, the increase in SiCp content will impact the compactness of the composites.

Microstructure and mechanical properties of the Mg–Zn–Cu/SiCp composite in the as-cast and as-extruded conditions

Abstract

Phase Evolution - Property Relationships of PIMed 5 - 40 Vol.% SiCp - Reinforced Aluminium Composite

Microstructure-mechanical property relationships of powder injection molded aluminium composite reinforced with 5 - 40 vol.% silicon carbide particulate (SiCp) has been investigated via thermal and phase analyses along with density and hardness testing. The samples were injection molded and sintered at 645 - 800 °C in N2 atmosphere. Thermal analysis showed endothermic reactions around 632 - 643 °C, related to liquid phase formation. Exothermic reactions about 458 - 461 °C and weight gains around 471 - 479 °C were plausibly associated with AlN formation, which facilitated liquid phase sintering. The composite microstructure exhibited close interfaces between SiCp - Al and Al - Al for 5 - 20 vol.% SiCp addition. Higher SiCp addition however led to SiCp clustering, creating large pores and unreacted SiCp - SiCp interface, which prohibited both liquid flow and rearrangement of the solid grains and pore filling during liquid phase sintering. Optimum SiCp addition was achieved at 15 vol.%, giving the maximum bulk density at 2.68 g.cm−3 or at 94.2 % theoretical density. The maximum macro Vickers hardness values at 138.9 and 166.6 Hv were obtained in the as - sintered and age - hardened conditions respectively.

Effect of Na3AlF6 Addition and Surface Modification of SiCp on the Microstructure and Mechanical Properties of SiCp/Al Composites

Al-matrix composites reinforced with 56.5 vol% SiC were prepared by powder metallurgy with different amounts of additives and surface modifications of SiCp. The crystalline phase, morphology, elements on the surface of SiCp and the interface between SiCp and Al were characterized by XRD, SEM, EDS and EPMA. The results show that it is favorable for the reaction between TiO2-C on the surface of SiCp and Al at the SiCp-Al interface at 1 050 °C. Besides, the process of Na3AlF6 melting, dissolving and then contacting with Al2O3 formed the NaF-AlF3-Al2O3 system, which generated OAlF2−, promoting the dessolution of Al2O3 film on the surface of Al powder. Na3AlF6 meets the needs of chemical reaction in TiO2-C-Al system at the SiCp-Al interface in the way of offering more molten Al. After 0.75 wt% Na3AlF6 was added into raw materials, the whole TiO2-C film and most SiO2 film were destroyed and the interfacial bonding between SiCp and Al was keeping good, in which no obvious void and crack were observed. Meanwhile, no brittle Al4C3 phase formed in the system. At this time, the flexure strength and density of samples presented optimal values, reaching up to 106.5 MPa and 90.77% respectively.

Dynamic Compressive Property of Closed-Cell Mg Alloy Composite Foams Reinforced with SiC Particles

The high-strain-rate mechanical response of Mg alloy/SiCp composite foams has received increased attention in recent years due to their light weight and potential to absorb large amounts of energy during deformation. Dynamic compressive properties of closed-cell Mg alloy/SiCp composite foams with different relative densities (0.162, 0.227 and 0.351) and different SiCp additions (0, 4 and 8 wt%) have been investigated using Split-Hopkinson pressure bar. It is shown that peak stress and energy absorption capacity significantly increase as the relative density increases at the range of testing strain rates. Peak stress and energy absorption display strain rate dependence. The peak stress of specimens with 0 wt% and 4 wt% SiC particles additions grows with increasing strain rate. Meanwhile, the increment in the peak stress of specimens with 8 wt% addition is not significant with strain rate increasing. The increase in strain rate increases the energy absorption capacity. The suitable amount of SiC particles addition has great advantages over increasing the peak stress and energy absorption capacity at the high strain rate. The strain-rate-sensitive matrix, cell morphology, morphological defects and gas pressure have an impact on the strain-rate sensitivity of Mg alloy/SiCp composite foams.

Effect of doping SiC particles on cracks and pores of Al2O3–ZrO2 eutectic ceramics fabricated by directed laser deposition

Melt growth Al2O3–ZrO2 eutectic ceramic has excellent high-temperature strength, creep resistance, oxidation resistance and ultra-high-temperature microstructural stability, which is expected to become one of the ideal high-temperature structural materials. Directed laser deposition (DLD) is a new technology for fabrication of melt growth eutectic ceramics, which can rapidly fabricate net-shaped ceramics. Aiming at decreasing crack and pore defects in samples prepared by DLD, different proportions of SiC particles (SiCp) are doped into Al2O3–ZrO2. Results show that SiCp distributes uniformly in Al2O3–ZrO2 eutectic ceramic matrix. Interfacial reaction occurs between SiCp and matrix. Two kinds of white phases rich in C, Si, Zr elements are formed around SiCp, and they are closely bonded with SiCp and matrix. The number and the maximum length of cracks in sample decrease obviously with the addition of SiCp. When the content of SiCp increases from 0 to 25 wt%, the number of cracks decreases 93% and the maximum cracks length decreases 92%. Some energy dissipation mechanisms such as crack pinning, transgranular fracture, crack deflection and bifurcation have remarkable effect on crack suppression. In addition, SiCp plays a significant role in eliminating pores, which reduces the porosity from 11.71 to 0.20%. Doping SiCp can increase the temperature and enhance the convection and disturbance of melt pool. Also, it can provide discharge channels for bubbles in melt pool.

Synthesis of Nanocrystalline AZ91 Magnesium Alloy Dispersed with 15 vol.% Submicron SiC Particles by Mechanical Milling.

The development of a magnesium matrix composite with a high content of dispersions using conventional liquid-phase process is a great challenge, especially for nanometer/submicron particles. In this work, mechanical milling was employed to prepare nanocrystalline AZ91 dispersed with 15 vol.% submicron SiC particles (SiCp/AZ91). AZ91 with no SiCp was applied as a comparative study with the same mechanical milling. In order to investigate the mechanism of dispersing, the morphology evolution of powders and the corresponding SiCp distribution were observed. As the scanning electron microscope (SEM) analysis exhibited, the addition of SiCp accelerated the smashing of AZ91 particles, which promoted the dispersion of SiCp in AZ91. Thus, after mechanical milling, 15 vol.% SiCp, which was smashed from 800 to 255 nm, got uniformly distributed in the Mg matrix. Based on X-ray diffraction (XRD) results, part of the Mg17Al12 precipitate got dissolved, and an Al-supersaturated Mg solid solution was formed. The transmission electron microscopy (TEM) results showed that the ultimate Mg grain (32 nm) of milled SiCp/AZ91 was much smaller than that of milled AZ91 (64 nm), which can be attributed to a pinning effect of submicron SiCp. After mechanical milling, the hardness of SiCp/AZ91 reached 185 HV, which was 185% higher than the original AZ91 and 33% higher than milled AZ91, due to fine Mg grain and submicron dispersions.

Microstructures, interface structure and room temperature tensile properties of magnesium materials reinforced by high content submicron SiCp

Abstract The present work aims to research the treatment processing of magnesium reinforced with 1 μmsilicon carbide particle (SiCp) using stir casting combined by ultrasonic vibration. Present studies have been done on six different materials: (a) AZ31B alloy without particles, (b) 5 vol.% SiCp/AZ31B composites fabricated with different semi-solid stirring time (5 min, 10 min, 15 min and 20 min), (c) composite with 20 vol.% SiCp. The effects of 1 μm/SiCp pretreatment and stirring time on microstructure and interfacial wettability as well as mechanical properties of the materials were confirmed. Both short and long stirring time for the particle dispersion brought particle agglomeration. Results of SEM microstructure and tensile properties exhibited that the optimal stirring parameters of 625 °C/1500 rpm/15 min are exploited, and 20 vol.% SiCp/AZ31B composite was fabricated by the optimal stirring parameters. The application of optimal stirring parameters for the treatment resulted in homogeneous particle distribution. The addition of SiCp leads to a reduced matrix grain, and 20 vol.% SiCp/AZ31B composite showed smaller grain size than. 5 vol.% SiCp/AZ31B composite. The interface between SiCp and matrix is clear and interfacial wettability well. Tensile test results show that with increasing SiCp content, strengths increase while ductility decreases.

Microstructure and mechanical properties of SiCp/ZL105 composite prepared by electromagnetic stirring

Aluminum matrix composites reinforced with SiC particles (SiCp) were prepared by electromagnetic stirring. This article aims to study the effects of SiCp addition on microstructure and mechanical properties of SiCp/ZL105, finally leading to expended range for ZL105 alloy application. Microstructural studies were carried out by optical microscope, scanning electron microscopy, and energy dispersive spectrometer. Tensile and hardness tests were conducted in order to identify mechanical properties. It was found that addition of 1.5 wt% SiCp causes the refined microstructure (including primary α-Al and eutectic Si) and reduced secondary dendrite arm spacing of α-Al matrix (12.6 μm). Compared to the ZL105 alloy, the ultimate tensile strength, elongation, and hardness of the composite with 1.5 wt% SiCp were increased by 24.6%, 37.3%, and 27.0%, respectively. The improved mechanical properties can mainly be attributed to the refinement of primary α-Al and eutectic Si, and uniformed dispersion of SiCp. Furthermore, the effects of voltage and agitation frequency of magnetic field on microstructure of composites were discussed.

Aging behavior of the extruded SiCp-reinforced AZ91 Mg alloy composite

Abstract

Effect of SiC<sub>p</sub> Addition on Microstructure and Mechanical Properties of ZTA Ceramics by Microwave Sintering

The effects of SiCp addition on the microstructure and mechanical properties of ZTA ceramics was investigated by microwave sintering. Partially stabilized zirconia（3Y-ZrO2）nanopowder containing SiCp was prepared by microwave pyrolysing precursor which was was achieved by co-precipitation method. The powders of alumina, yttria partially stabilized zirconia containing SiCp were mixed to prepare ZTA ceramics green body by die pressing and cold isostatic pressing and subsequently sintered at the range of 1350°C-1550°C for 30min by microwave. XRD revealed that 3Y-ZrO2/SiC powder contained more tetragonal phase than 3Y-ZrO2 powder which was also confirmed by SEM and particle size distribution. The phenomenon was because of SiCp forming the microwave heating spot that promoted pyrolysis progress when 3Y-ZrO2/SiC powder was prepared by microwave heating. Microstructure showed that the grain of ZTA ceramics had directional growth by microwave sintering. SiCp firstly absorbed microwave that made more uniform sintering of ZTA ceramics and caused local oriented growth of zirconia and alumina. Thus, the bending strength of ZTA ceramics was higher than ZTA without SiCp. The ladder type heating mode of microwave sintering ZTA ceramics reduced relatively sintering time by 20min due to the addition of SiCp.Introduction

Effects of SiCp Content on the Microstructure and Mechanical Properties of SiCp/Mg-5Al-2Ca Composites

The Mg-5Al-2Ca alloys reinforced by 2vol%, 5vol% and 10vol% 5 μm SiCp were fabricated by stir casting. The cast composites were subject to hot extrusion. In the cast composites, addition of SiCp disturbs the network distribution of Al2Ca phase along grain boundaries. After extrusion, grains of the matrix are refined further and the Al2Ca phase break into particulates. Moreover, the Al2Ca phase and grain size can be further refined by the addition of SiCp. Compared with Mg-5Al-2Ca alloy, the addition of SiCp introduces obvious improvement of tensile yield strength (TYS) and work hardening rate, however, at the expense of elongation. Unlike the TYS, the ultimate tensile strength (UTS) of SiCp/Mg-5Al-2Ca composite does not change monotonously with increasing SiCp's content, and the highest UTS appears when the SiCp's volume fraction is 5%. The interfacial debonding between SiCp and Al2Ca phase and cracked particles are considered as the main crack source for SiCp/Mg-5Al-2Ca composite.

Microstructures and mechanical properties of SiCp/Mg-xAl-2Ca composites collectively influenced by SiCp and Al content

The SiCp/Mg-xAl-2Ca composite with different (2, 3, 5 and 9 wt%) Al content is fabricated by stir casting. After be extruded at 673 K with the ratio of 16:1, the microstructures and mechanical properties of the composites are investigated. As compared with Mg-xAl-2Ca alloys, the addition of SiCp has no obvious effect on the category of precipitated phase, but increases its volume fraction and is propitious to the uniformity of microstructures. With the application of extrusion, precipitated phase is refined and its distribution is improved obviously. The yield strength of the composites increases with the increasing of Al content as a result of an increased amount of precipitated phase. The ultimate tensile strength and elongation are improved as the Al content increased from 2 wt% to 5 wt%, but deterioration happens when the Al content is increased to 9 wt%. Addition of SiCp lows down the strength of Mg-2Al-2Ca alloy, however, leads to the increased strength of Mg-3Al-2Ca alloy and Mg-5Al-2Ca alloy. Even though the yield strength of SiCp/Mg-9Al-2Ca composite is similar to Mg-9Al-2Ca alloy, it owns a lower ultimate tensile strength.

Liquid-Phase Sintering and Properties of PIMed 10-20 vol.% SiCp-Reinforced Aluminium Composites

Liquid-phase sintering and properties of powder injection moulded aluminium composite reinforced with SiCp has been investigated via thermal-phase analyses and hardness property. Mixing of 10 and 20 vol.% SiCp and aluminium powder was done via ball milling prior to feedstock preparation at 55% solid loading. Powder injection moulding was carried out at 170°C, followed by solvent and thermal debinding. The brown samples were sintered in a nitrogen atmosphere at 650–660°C, prior to age-hardening. Experimental result shows relatively high % linear shrinkage of 9.9–21.9 % and high % volumetric shrinkage of 34.5–46.5%. Thermal analysis indicates the formation of the liquid around 632 °C, facilitating liquid phase sintering. The composite microstructures consists of uniformly distributed SiCp throughout the densified aluminium matrix. SiCp addition scales up SiCp clustering, accompanying with gap porosity. The composite reinforced with 10 vol.% SiCp possesses higher sintered density at 2.63 g/cm3, yielding 93.1% theoretical. However the maximum macro Vickers hardness was measured at 164.2 Hv for 20 vol.% SiCp – reinforced aluminium composite in the age-hardened condition. Liquid phase sintering was found effective for the microstructure evolution of the PIMed composite, rendering densification. Hardening is influenced by SiCp addition and the roles of AlN, Al2Cu and Mg2Si precipitates.