Ceramic Reinforcement Research Articles

Structure of VT6 – SiC composite material

To date, the methods of additive technologies for manufacturing goods are applying more and more widely in the real sector of production and are rapidly developing. The development of various composite materials by these methods is of increased interest, since it has become possible to obtain composite materials with a different number of initial components of the matrix and reinforcer. It became possible to integrate ceramics into a metal matrix and vice versa by growing products from raw powder materials variously composed. The resultant materials may be used as a replacement for existing ones, since they have a cumulative unique set of properties that are necessary for technological and scientific expansion. Combination of well-known technologies, such as classical hot isostatic pressing, selective laser melting and ceramic fiber reinforcement, will make it possible to obtain unique composite materials. Thin-walled products from titanium alloys, including thin sections, may be obtained by the use of selective laser melting. The main problems in manufacturing of fiber-reinforced materials are setting the fibers in a given position, minimizing their displacement during consolidation, as well as limiting the matrix and fiber interaction during consolidation to prevent a reaction with the formation of an interaction zone. In order to create a new material, a silicon carbide reinforcing fiber was loaded into the shaped manufactured article, followed by encapsulated hot isostatic pressing. As a result, effective diffusion connections of individual matrix elements took place, as well as complete enveloping the fibers with the matrix material. A low-porosity structure without large defects visible on X-ray tomography was obtained.The work was carried out with the financial support of the Ministry of Science and Higher Education of the Russian Federation under the Grant agreement No. 075-11-2019-058 dated 25.11.2019 “Organization of production of locally reinforced parts made of titanium alloys operating under conditions of increased loads and temperatures for advanced aviation gas turbine engines”, approved by the Decree No. 218 of the Government of the Russian Federation.

The modeling and mechanical properties prediction of whisker-reinforced ceramic composites

Whiskers have been extensively used in ceramics as excellent reinforcing phases during the past decades. Despite in-depth investigation of whisker-reinforced ceramics (WRC), however, the time-consuming, environmentally unfriendly, content design blindness of experimental method as well as pathogenicity of whiskers force people to explore quick and green research approaches. Therefore, this work aims at developing a modeling approach of WRC and predicting the mechanical properties of WRC, thereby compensating for the disadvantages of traditional experimental method. Initially, a modeling approach of WRC based on Voronoi tessellation was presented. Then, taking β-Si3N4w and Si3N4 as research objects, the prediction models of mechanical properties of 0–6 wt% β-Si3N4w-reinforced Si3N4 ceramics (SWRSC) were established. Finally, the effect of β-Si3N4w content on mechanical properties of Si3N4-based ceramics was discussed, and the enhancement mechanism of β-Si3N4w was revealed. Results indicated that the flexural strength of SWRSC was significantly advanced with increasing β-Si3N4w content. Crack deflection and intergranular fracture induced by β-Si3N4w as well as load-bearing effect of β-Si3N4w were the mainly responsible for the reinforcement of Si3N4-based ceramics. The enhancement mechanisms, previously observed experimentally, were effectively simulated. The fracture toughness reached a maximum of 6.17 MPa m1/2 when β-Si3N4w amount was 1 wt%, which was approximately 36.50% higher than monolithic Si3N4 ceramic. The predicted value of β-Si3N4w optimal content was consistent with relevant experimental conclusions. When β-Si3N4w content was 3 wt%, the hardness of Si3N4-based ceramics reached the maximum value of 23.21 GPa. The effectiveness of prediction results and the presented modeling method were confirmed by comparing with related test values.

Magnesium Based Hybrid Nanocomposites: An Insight into Nanoparticle Effects on the Microstructure and Mechanical Properties

Aims: The primary aim of this research is to understand the effects of type of nanoparticles on the microstructure and mechanical properties of Mg-based hybrid nanocomposites. For this reason, new Mg-based hybrid nanocomposites containing 2.2 vol.% Ti and 1.1 vol.% nano-Al2O3 or nano B4C particles were synthesized and their properties were studied in comparison with Mg-Ti and pure Mg. Background: Magnesium with excellent weight-saving potential is ideal for automotive and aerospace applications. But its use in pure Mg is restricted due to inherent limitations such as poor absolute strength, elastic modulus, deformability, and corrosion susceptibility. While most of these limitations can be circumvented by the judicious addition of micron-sized ceramic reinforcements, ductility is often compromised. One of the promising ways for ductility enhancement involves the use of nano-length scale reinforcements. Similar ductility improvements were also reported when hybrid reinforcements were introduced into the Mg matrix. While the role of hybrid reinforcement preparation, the particle size distribution, and volume fraction of hybrid reinforcements were studied extensively in the past, no detailed investigation on the effects of type of nanoparticles has been conducted so far. Objective: The objectives of this research include the successful synthesis and property characterization of Mg-based hybrid nanocomposites containing hybrid (Ti+Al2O3 or Ti+B4C) reinforcements. Result: While both hybrid nanocomposites displayed fine grains when compared to pure Mg and Mg-Ti, there was no noticeable difference between the grain size distribution profiles of Mg- (Ti+Al2O3) and Mg-(Ti+B4C) hybrid composites. The results of property measurements indicated an improvement in dimensional stability, indentation, tension, and compression properties of Mg due to the addition of either individual Ti or hybrid (Ti+Al2O3) or Mg-(Ti+B4C) particles. Among the hybrid composites, Mg-(Ti+B4C) containing hybrid (Ti+B4C) reinforcement exhibited a better combination of strengths and ductility. While the inherent strengthening contribution from B4C and Al2O3 reinforcements resulted in slightly different strength properties, the ductilization benefits of boron compounds enhanced the tensile fracture strain of Mg-(Ti+B4C). Conclusion: Since the particle size distribution and volume fraction of (Ti+Al2O3) and (Ti+B4C) are similar, the difference in strength values between Mg-(Ti+Al2O3) and Mg-(Ti+B4C) can be attributed to the matrix strengthening contribution from reinforcement type.

Microstructural and compositional evolution of SAC305/TiN composite solder under thermal stressing

PurposeThe purpose of this paper is to investigate the effect of titanium nitride (TiN) on microstructure and composition of 96.5Sn3Ag0.5Cu (SAC305) lead-free solder joints under a large temperature gradient.Design/methodology/approachIn this paper, SAC305 lead-free composite solder containing 0.05 Wt.% TiN was prepared by powder metallurgy method. A temperature gradient generator was designed and the corresponding samples were also prepared. The microstructural evolution, internal structure and elemental content of SAC305 and SAC305/TiN solder joints before and after thermal loading were comparatively studied.FindingsThe experimental results show that the addition of the TiN reinforcing phase can effectively inhibit the diffusion and migration of copper atoms and, therefore, affect the distribution of newly formed Cu-Sn IMC in solder joints under the condition of thermal migration (TM). Compared with the SAC305 solder joint, the interconnection interface and internal structure of the composite solder joint after 600 h of TM are also relatively complete.Originality/valueThe TiN reinforcing phase is proven effective to mitigate the TM behavior in solder joints under thermal stressing. Specifically, based on the observation and analysis results of microstructure and internal structure of composite solder joint, the TiN particle can change the temperature gradient distribution of the solder joint, so as to suppress the diffusion and migration of Sn and Cu atoms. In addition, the results of Micro-CT and compositional analysis also indicate that the addition of TiN reinforcement is very helpful to maintain the structural integrity and the compositional stability of the solder joint. Different from other ceramic reinforcements, TiN has good thermo- and electro-conductivity and the thermal-electrical performance of composite solder will not be significantly affected by this reinforcement, which is also the main advantage of selecting TiN as the reinforcing phase to prepare composite solder. This study can not only provide preliminary experimental support for the preparation of high reliability lead-free composite solder but also provide a theoretical basis for the subsequent study (such as electro-thermo distribution in solder joints), which has important application significance.

The reinforcement mechanisms of graphene oxide in laser-directed energy deposition fabricated metal and ceramic matrix composites: a comparison study

Carbon-based nanomaterials mainly including carbon nanotubes (CNTs), graphene, and graphene oxide (GO) have superior properties of low density, outstanding strength, and high hardness. Compared with ceramic reinforcements, small amount of carbon-based nanomaterials can significantly improve the mechanical properties of metal matrix composites (MMCs) and ceramic matrix composites (CMCs). However, CNTs and graphite always aggregate or degrade during the fabrication with a high temperature, especially in MMCs. GO has the advantages of easier to be dispersed in other materials and better high-temperature stability. Laser-directed energy deposition (DED) has been used to fabricate GO-MMCs and GO-CMCs due to the unique capabilities of coating, remanufacturing, and producing functionally graded materials. Laser DED, as a fusion manufacturing process, could fully melt the material powders, which could refine the microstructure and increase the density and mechanical properties. However, GO could react with matrix materials at high temperatures. The survival, degradation, and reactions of GO in laser DED fabricated GO-MMCs and GO-CMCs are still unknown. There is also no investigation on the reinforcement mechanisms of GO in metal matrix materials and ceramic matrix materials in the laser DED process. In this study, GO-reinforced Ti (GO-Ti) and GO-reinforced zirconia toughened alumina (GO-ZTA) parts were fabricated by laser DED process. Raman spectrum, XRD analysis, and EDS analysis have been applied to investigate the forms of GO in both DED fabricated GO-MMCs and GO-CMCs. The reinforcement mechanisms of GO on microhardness and compressive properties of MMCs and CMCs have been analyzed.

Comparison of wear behaviour of LM13 Al−Si alloy based composites reinforced with synthetic (B4C) and natural (ilmenite) ceramic particles

Dry sliding wear behaviour of stir-cast aluminium matrix composites (AMCs) containing LM13 alloy as matrix and ceramic particles as reinforcement was investigated. Two different ceramic particle reinforcements were used separately: synthetic ceramic particles (B4C), and natural ceramic particles (ilmenite). Optical micrographs showed uniform dispersion of reinforced particles in the matrix material. Reinforced particles refined the grain size of eutectic silicon and changed its morphology to globular type. B4C reinforced composites (BRCs) showed maximum improvement in hardness of AMCs. Ilmenite reinforced composites (IRCs) showed maximum reduction in coefficient of friction values due to strong matrix−reinforcement interfacial bonding caused by the formation of interfacial compounds. Dry sliding wear behaviour of composites was significantly improved as compared to base alloy. The low density and high hardness of B4C particles resulted in high dislocation density around filler particles in BRCs. On the other hand, the low thermal conductivity of ilmenite particles resulted in early oxidation and formation of a tribo-layer on surface of IRCs. So, both types of reinforcements led to the improvement in wear properties of AMCs, though the mechanisms involved were very different. Thus, the low-cost ilmenite particles can be used as alternative fillers to the high-cost B4C particles for processing of wear resistant composites.

Nickel-titanium based nanocomposites for orthopedic applications: the effects of reinforcements

Owing to better mechanical properties and shape memory effect, the nickel-titanium (NiTi) alloy is a favorable material for orthopedic implants. However, low wear resistance and limited biocompatibility of NiTi can be enhanced by nano-sized reinforcements. Several NiTi-based nanocomposites are developed using nano-sized ceramic reinforcements. Similarly, bioceramic (i.e., HAp) reinforced NiTi nanocomposites are also developed to improve their bioactive properties. However, these nanocomposites show high interconnected pores that severely affect their mechanical strength, corrosion resistance, and biocompatibility. Therefore, some further improvements are required to balance the mechanical and biological properties of NiTi-based nanocomposites. This paper provides a better understanding of NiTi-based nanocomposites developed for orthopedic applications and the resultant effects of nano-sized reinforcements on mechanical, wear, corrosion, biocompatible and bioactive properties. Besides, the synthesis of NiTi nanocomposites using the powder metallurgy process and the effects of process parameters on the nanocomposite properties were also discussed.

Optimization of casting parameters for improved mechanical properties of eggshell reinforced composites

Abstract The tensile strength, hardness and toughness of any materials are the most important mechanical properties in the selection of materials for varied industrial applications. In the development of aluminum based composite material, tensile strength and hardness were significantly improved by adding various ceramic reinforcement particles. However, toughness was reduced. In this research work, an attempt was made to enhance tensile strength, hardness and toughness simultaneously by using carbonized eggshell as reinforcement material developed via electromagnetic stir casting. The process parameters used in this study are the matrix pouring temperature, wt.-% of the reinforcement; preheat temperature, stirring current and stirring time. Response surface methodology (RSM) is used for conducting the experiment. The multi-objective optimization technique utility theory is employed to optimize the combined mechanical properties viz. tensile strength, hardness and toughness. Microstructure results show that at the optimum level of process parameters, eggshells are uniformly distributed. Confirmation tests are conducted to validate the experimental results. Experimental results revealed that at optimum process parameters, hardness and tensile strength are significantly improved without affecting the toughness property of the composite. The optimum level of process parameters to enhance all mechanical properties (tensile strength, hardness and toughness) were found to be a reinforced preheating temperature of about 448.32 °C, a stirring current of about 11.64 A, a stirring time of about 63.64 s, a maximum pouring temperature of about 800.24 °C and a percentage of eggshells of about 9.16 %. The novelty of this work lies in the fact that no attempt was made to optimize these electromagnetic process parameters. Corrosion loss, thermal expansion behavior and a wear test were investigated to observe the effect of adding eggshell at optimum electromagnetic stir casting parameters.

Strong and tough Al2O3–MgO–C refractories with dispersed aluminosilicate reinforcement

Resin–bonded Al2O3–MgO–C refractories were fabricated with dispersed aluminosilicate reinforcement. The reinforced systems were strong and tough to thermal shock failures over the standard components without reinforcement. MOR measurements showed that the shocked refractories with reinforcement were failed with a maximum strength of 20 MPa, indicating 200% increase of their load bearing capacity. Toughness and fracture surface energy improvements predicted that the shocked systems reinforced with aluminosilicate particulates exhibit three times enhanced resistance to mutual crack growth over the standard. All these beneficial properties indicate a satisfactory thermal shock performance, which is credited to the effective operation of dispersion strengthening\\viscoelastic bridging effects offered by a flaw–tolerant microstructure formed in all parts of the refractory oxidized layer fortified with dispersed aluminosilicate reinforcement. Additionally, implications of these results to microstructure design of various classes of carbon containing refractories in MgO–C\\Al2O3–C systems formulated with carbon\\ceramic reinforcements are proposed.

Ultrasound-Assisted Surface Modifications on Ceramic Reinforcement for Lead-Free Composite Solders : Short Review

The purpose of this paper is to review and examine the effect of ultrasound-assisted surface modifications of ceramic reinforcements on the properties of lead-free solders. The discussion will highlight the fundamental understanding, main parameters, configurations, and recent surface-modified ceramic reinforced composite lead-free solder developments. The review also identified and summarized the advantages, current trends, and significant findings in this field. The ultrasound-assisted surface modification was found to provide a crucial improvement on the wettability properties of molten solders as the matrix phase on the ceramic reinforcement. Further, the excellent distribution of ceramic reinforcement in solder matrix was also seen after the surface modification process. This has led to significant improvements in mechanical properties such as hardness and strength. The pinning of dislocation movement was seen as the reason for improving the mechanical properties. This positive impact in enhancing the ceramic reinforcement-solder interfacial reaction allows more explicit future research directions and opportunities for composite solder applications.

Evaluation on Mechanical Properties of Coated RHA-TIO2-LM24 Aluminium Alloy Composite

Abstract: In the present research work, liquid state technique is employed to prepare the LM4/RHA/TiO2 composites containing four different mass proportion of RHA and TiO2. The weight proportion of reinforcements ie RHA-1,3&5 and TiO2 2,5&6 respectively. Hybrid composite with 3% of RHA and 6% of TiO2 showed the maximum Tensile strength of 298.37 N/mm².It is found that there is 37 % increase of tensile strength while addition of RHA and TiO2 to LM 24.The aluminium based particulate reinforced composite, the dislocations are generated during solutionizing due to thermal mismatch between the matrix and the ceramic reinforcement particles. It can be inferred that the tensile strength increased with an increase in the weight percentage of rice husk ash and TiO2. Because, the RHA particles act as barriers to the dislocations when taking up the load applied. It has been observed that with changing rate of TiO2 compressive quality increments from 478.83 to 653.79 MPa. The increase in compressive strength is mainly due to the decrease in the inter-particle spacing between the particulates since RHA and TiO2 are much harder than LM24. The presence of RHA and TiO2 resists deforming stresses and thus enhancing the compressive strength of the composite material. The maximum hardness value obtained for 5 wt.% of RHA and 6 wt.% of TiO2 .ie.117 BHN. It was observed that the hardness of the composite linearly increasing with the increase in weight fraction of the rice husk ash particles. This occurs due to increases in surface area of the matrix and thus the grain sizes are reduced. The presence of such hard surface area offers more resistance to plastic deformation which leads to increase hardness.. Keywords: LM4/RHA/TiO2, Tensile testing, Compression, Hardness, Rice husk.

Synthesis of Ceramic Reinforcements in Metallic Matrices during Spark Plasma Sintering: Consideration of Reactant/Matrix Mutual Chemistry

Metal–ceramic composites are obtained via ex-situ or in-situ routes. The in-situ route implies the synthesis of reinforcement in the presence of a matrix and is often regarded as providing more flexibility to the microstructure design of composites than the ex-situ route. Spark plasma sintering (SPS) is an advanced sintering method that allows fast consolidation of various powder materials up to full or nearly full density. In reactive SPS, the synthesis and consolidation are combined in a single processing step, which corresponds to the in-situ route. In this article, we discuss the peculiarities of synthesis of ceramic reinforcements in metallic matrices during SPS with a particular consideration of reactant/matrix mutual chemistry. The formation of carbide reinforcements in Cu, Al, and Ni matrices is given attention with examples elaborated in the authors’ own research. Factors determining the suitability of reactive SPS for manufacturing of composites from a matrix/reactants system and features of the structural evolution of the reaction mixture during sintering are discussed.

Enhancing mechanical properties of copper matrix composite by adding SiO2 quantum dots reinforcement

Silica/Cu composites generally fail to achieve the high strength due to the weak interfacial bonding between SiO2 and Cu. In the current work, the first use of silica quantum dots (SiO2 QDs) as a copper-based composite reinforcement. Silicon quantum dots (Si QDs) and copper acetate are employed as raw materials for spray pyrolysis to obtain an interconnected structure of SiO2 QDs/Cu2O, which achieve well-dispersion of the reinforcement and good interface combination in one step. The SiO2 QDs/Cu2O composite block is obtained by ball milling, hydrogen reduction, and SPS sintering. Micro interface structure and strengthening mechanism of the composites are investigated and presented in detail. Microstructural analysis discovers the Cu2O transition layer between SiO2 QDs and Cu matrix and well-dispersed SiO2 QDs in the Cu matrix. The good bonding of grain interface can significantly enhance the mechanical properties. The 1.2 wt% SiO2 QDs/Cu composite block exhibits an excellent ultimate tensile strength of 456.63 MPa, which is 101.68% higher than that of unreinforced Cu (227.39 MPa). Furthermore, the composite block maintains the high conductivity (83.27% IACS) and elongation (8.86%). Moreover, this work can promote the development of Cu matrix composites using ceramic reinforcement with an improved interface bonding.

Matrix Composite Coatings Deposited on AISI 4715 Steel by Powder Plasma-Transferred Arc Welding. Part 3. Comparison of the Brittle Fracture Resistance of Wear-Resistant Composite Layers Surfaced Using the PPTAW Method.

This article is the last of a series of publications included in the MDPI special edition entitled “Innovative Technologies and Materials for the Production of Mechanical, Thermal and Corrosion Wear-Resistant Surface Layers and Coatings”. Powder plasma-transferred arc welding (PPTAW) was used to surface metal matrix composite (MMC) layers using a mixture of cobalt (Co3) and nickel (Ni3) alloy powders. These powders contained different proportions and types of hard reinforcing phases in the form of ceramic carbides (TiC and WC-W2C), titanium diboride (TiB2), and of tungsten-coated synthetic polycrystalline diamond (PD-W). The resistance of the composite layers to cracking under the influence of dynamic loading was determined using Charpy hammer impact tests. The results showed that the various interactions between the ceramic particles and the metal matrix significantly affected the formation process and porosity of the composite surfacing welds on the AISI 4715 low-alloy structural steel substrate. They also affected the distribution and proportion of reinforcing-phase particles in the matrix. The size, shape, and type of the ceramic reinforcement particles and the surfacing weld density significantly impacted the brittleness of the padded MMC layer. The fracture toughness increased upon decreasing the particle size of the hard reinforcing phase in the nickel alloy matrix and upon increasing the composite density. The calculated mean critical stress intensity factor KIc of the steel samples with deposited layers of cobalt alloy reinforced with TiC and PD-W particles was 4.3 MPa⋅ higher than that of the nickel alloy reinforced with TiC and WC-W2C particles.

Pre-oxidation induced in situ interface strengthening in biodegradable Zn/nano-SiC composites prepared by selective laser melting

IntroductionNano-SiC has attracted great attention as ceramic reinforcement in metal matrix composites, but the weak interface bonding between them remains a bottleneck for efficient strengthening. ObjectiveIn this study, pre-oxidation treatments and selective laser melting (SLM) were employed to prepare Zn/nano-SiC biocomposites with strengthened interface bonding via in situ reaction. MethodsNano-SiC and Zn powders were pre-oxidized respectively, and then used to prepare Zn/nano-SiC biocomposites via SLM. The powder microstructure, and the interface characteristics and mechanical properties of the biocomposites were investigated. The degradation properties and cell response were analyzed to evaluate their feasibility for orthopedic applications. ResultsThe results indicated that the pre-oxidation treatments generated a uniform oxide layer on the surface of both nano-SiC and Zn particles and the thickness of the oxide layer increased with pre-oxidation temperature. During the SLM process, the oxide layers not only improved the metal-ceramic wettability by reducing interface energy, but also induced in situ reaction to form chemical bonding between the Zn matrix and nano-SiC, thereby improving the interface bonding. Consequently, the Zn biocomposite reinforced by nano-SiC with a pre-oxidation temperature of 1000 °C (ZS1000 biocomposite) exhibited more transgranular fracture and significantly enhanced compressive yield strength of 171.5 MPa, which was 31.6% higher than that of the Zn biocomposite reinforced by nano-SiC without pre-oxidation. Moreover, the ZS1000 biocomposite presented slightly accelerated degradation which might be ascribed to the facilitated electron transfer by the interface product (Zn2SiO4). In addition, the ZS1000 biocomposite also showed appropriate biocompatibility for MG-63 cell adhesion, growth, and proliferation. ConclusionThis study shows the potential practical applicability for the preparation of Zn-based biocomposites with strong interface bonding and mechanical properties for orthopedic applications.

Microstructures and properties of Ti/TiC composites fabricated by laser-directed energy deposition

Titanium/Titanium Carbide (Ti/TiC) composites with 20, 40 and 60 vol% of TiC powders were deposited on Ti-6Al-4V substrates using a laser-directed energy deposition method. The bulk relative densities exceeding 99% were achieved in the deposits. The evolution of microstructures and local chemical compositions in the deposits under rapid melting and solidification were analyzed using X-ray diffraction, electron probe micro-analyzer and scanning electron microscopy. Assessment of mechanical integrity of the deposits involved microhardness, tensile testing and fractography. The deposition process resulted in defect-free deposits with 20% TiC. However, cracks were observed originating from the substrate/deposit interface in the 40% and 60% TiC deposit. The L -DED process caused only partial dissolution of the initial TiC particles and the amount of undissolved particles in the deposited matrix increased with increasing TiC volume fraction in the initial powder feedstock mixture. A non-stoichiometric TiC 0.55 compound was found to form during solidification. The solidified product in the deposits included dendritic and equiaxed TiC 0.55 precipitates homogeneously distributed in the matrix. Micro-hardness measurements indicated that hardness values increased monotonically with TiC content in the deposit. On the other hand, a gradient Ti/TiC composite with composition ranging between 20% and 60% TiC did not develop any growth cracks suggesting an efficient processing route for synthesizing MMCs with high volume fraction of brittle ceramic reinforcements. It was found that pre-existing cracks in the TiC used in the starting feedstock played a key role in the mechanical integrity of the deposits. This observation suggests that the mechanical performance of the Ti/TiC composite deposits can be improved using techniques that promote complete dissolution of the original TiC.

Interface characterization of Al/SiCp compacts

In the last decade, several authors and scientists are interested more and more to understand the phenomena which are take place at aluminum matrix and silicon-carbide interface. This type of composite material is especially used in aerospace and automotive industries which involve high temperature applications. Aluminum metal matrix composites containing 5,15,25 weight % SiCp were processed by powder mettalurgy route. The interaction between metallic matrix (aluminum) and particulate ceramic reinforcement (silicon-carbide) was studied. At the beginning the solid-state reaction behavior of the Al/SiC powder mixture compacts was investigated. The density, porosity, compressibility of Al-SiCp composites were calculated. Maximum densification of the composite material reinforced with 5% SiC is obtained at a compactation pressure of 420 MPa (94.5%). For 15% SiC content densification increase with higher compactation pressure given the density values of 95.66% and 96.46% for the 25% SiC composite. Conventional scanning electron microscopy revealed a faceted interface between SiC particulate and Al matrix. This chemical reaction at the interface is the result of dissolution of silicon carbide particulates in aluminum matrix during the liquid sintering process at high temperature:1100,1300,1450 and 1750°C in different sintering atmospheres. For intermetallic compounds identification was used an energy dispersive X-ray spectroscopy (EDX) investigation. The presence of compounds and phases such as: Al4C3, Al4O4C, Al4SiC4, SiO2, Al2O3, confirmed by X-ray diffraction analysis is given by different sintering temperature. It is important to know the structure and chemical composition of the interface and near to the interface zone for study the mechanical properties of the reinforced metal matrix composites.

Effect of Synthesis Procedure on Particle Dispersion and Hardness of Al- Sic Functionally Graded Metal Matrix Composite

Abstract Fabrication of Functionally Graded Metal Matrix Composites (FGMMC) especially with high ceramic reinforcement's volume fraction is highly challenging. Depending on the processing technique and process parameters various defects may arise. This research aims to find the best procedure to make FGMMCs with the highest quality and minimum cost. A new method is proposed that incorporates lost-foam and melt infiltration with semicentrifugal casting to produce FGMMC. Experiments were performed to in-situ fabricate 6061-Aluminum alloy reinforced with gradient distributed Silicon carbide particles (Al/SiC FGMMC). Effect of SiC %, Al pouring temperature and rotational speed on the fabricated specimens hardness and reinforcement gradient were investigated using design of experiments and regression analysis. Results reveal the optimum procedure and process settings based on desired properties/gradient required. Mathematical model formulated captures the effect of these process parameters on process cost, and cost of poor quality. Improper selection of those parameters may lead to extensive losses due cost of poor quality which is 12 times higher than the material cost. The proposed manufacturing process proved satisfactory in ensuring proper dispersion. A desirability function can by used to determine the process parameters and volume fraction that minimizes the defects and gives superior properties for a specific application.

A Review on the Wear, Corrosion and High-Temperature Resistant Properties of Wire Arc-Sprayed Fe-Based Coatings.

Among different thermal spraying methods, arc-spraying has been widely used due to its low operating costs and high deposition efficiency. The rapid progress of cored wire technology in arc-spraying has increased possibilities for the preparation of new Fe-based coating materials with enhanced properties by adding reinforcement particles and alloying elements to suit the different applications. Fe-based coatings have been extensively used because of their high strength, toughness, lower production costs, and availability of raw materials. This makes them suitable replacements for Ni-based coatings in ambient and high-temperature applications. This review discusses the research status and developments of the arc-sprayed Fe-based coatings. The study specifically reviews the wear behavior, corrosion analysis, and high-temperature resistant properties of arc-sprayed Fe-based coatings, aiming to develop an understanding of the protection mechanisms for Fe-based coatings. The performance of the Fe-based coatings depends on the integrity of the coating structure. Optimizing arc-spraying parameters minimizes defects (pores, grain boundaries, unmelted particles, oxides, and microcracks) that deteriorate the coating properties. High amorphous phase content, ceramic reinforcement particles and alloying elements enhance the corrosion, tribological, and high-temperature resistant properties of Fe-based coatings. In high-temperature applications, Fe-based coatings form oxide scales that protect the coating from further oxidation; thus, it is important to select the optimum composition for the alloying elements.

Milling of an Aluminium Matrix Composite Using MCD-Tipped Tools with Adjusted Corner and Minor Cutting Edge Geometries

Aluminium matrix composites (AMCs) represent suitable materials for lightweight design applications. The abrasive ceramic reinforcements typically require diamond cutting materials to prevent excessive tool wear. In milling with diamond cutting materials the influence of cutting parameters was already examined to a significant extent. Investigations concerning the effect of modified tool geometries are limited and the potentials with regard to the geometrical and physical surface properties are unclear. Accordingly, experimental investigations in milling of a 10 vol.% SiC particle-reinforced aluminium wrought alloy EN AW-2017 T4 were addressed. The effect of modified corner and minor cutting edge geometries were investigated based on mono crystalline diamond (MCD)-tipped tools to benefit stable process conditions. The results indicated achievable areal roughness values in the range around 0.2μm. Especially the application of the lowest cutting edge angle and a trailing minor cutting edge led to strong fluctuations of the surface parameters. The lowest valley void volumes were achieved with an arched minor cutting edge. Generally, finish machining led to stronger compressive residual stresses compared to the state prior to machining. The strongest increase was achieved using a corner radius combined with a straight minor cutting edge. It is concluded that reduced effective radii generating the surface enable an acceptable surface structure and strong compressive residual stresses and should be addressed in further investigations.