Gas Pressure Infiltration Research Articles

Fabrication, microstructure, mechanical properties and wear behavior of Al/Cu-SiCw composite

This research investigates the production of Cu-SiCw composites by using gas pressure infiltration method and the production of Al/Cu-SiCw composite by using the cold rolling method. The layers were bonded by three rolling reductions of 40 %, 50 %, and 60 %. The microstructures of composites before and after roll bonding were discussed based on SEM and EBSD images. Less agglomeration of whiskers was seen after higher rolling reductions which indicates better distribution of reinforcement in copper. In addition, no decomposition and reaction were observed in Cu-SiCw. The effect of rolling reductions on hardness, wear behavior, and tensile properties was also investigated. Hardness, yield, and ultimate strengths increased at higher rolling reductions. The yield and ultimate strengths increased from 118 MPa to 227 MPa after a 40 % rolling reduction to 150 MPa and 263 MPa after a 60 % rolling reduction. The measured friction coefficient and mass loss showed better wear resistance of composites at higher rolling reductions because the layers became hardened. The mass loss decreases from 6.46 mg after a 40 % rolling reduction to 5.42 mg after a 60 % rolling reduction. Worn surfaces based on SEM images showed shallower grooves and less remaining debris.

Zero thermal expansion high-strength metallic glass-based composites

Materials with zero thermal expansion (ZTE) properties demonstrate remarkable dimensional stability, making them crucial in aerospace, electronics, and various industrial sectors. However, these materials face challenges such as weak mechanical properties and narrow ZTE temperature range. In this study, a novel ZTE metallic glass-based composite (Cu2P2O7/La65Al14Cu9.17Ag1.83Ni5Co5) with negative thermal expansion (NTE) reinforcement was prepared using gas pressure infiltration and water quenching. SEM and 3D CT results revealed the dense structure and the non-reactive interface structure. The NTE behaviors resulting from the coupling of CuO5 and PO4 polyhedra within the NTE Cu2P2O7 are demonstrated to counterbalance the positive thermal expansion in metallic glass. Consequently, the resulting composites exhibit a wide range of zero thermal expansion and high strength properties, presenting a novel approach for creating high-performance ZTE metallic glass-based composites.

Manufacturing and characterization of an interpenetrating metal matrix composite reinforced with a 3D-printed metallic glass lattice structure (Ni60Nb20Ta20)

Metallic glasses (MG) exhibit remarkable properties, like high strength, hardness, and elastic strain limit due their amorphous structure. But they also exhibit low ductility and brittle behavior, making them less suitable for monolithic components. Therefore, MG offer high potential for use as a reinforcing phase in a ductile matrix. Especially interpenetrating metal matrix composites (MMCs) are suitable, since good interfacial adhesion can be achieved due to the metallic character of the MG and mechanical properties can be further enhanced by the interpenetrating structure. Temperature during manufacturing process must be below crystallization temperature of the MG. Until now, interpenetrating MMCs have been manufactured by infiltrating the metal matrix foam with MG, requiring a high melting temperature of the matrix and thus excludes lightweight metals. In this work it was possible to infiltrate an open porous lattice structure of MG (Ni60Nb20Ta20) due to its high crystallization temperature with AlSi12 by gas pressure infiltration resulting in a novel MMC. X-ray diffraction measurements confirm that no crystallization occurred during infiltration. Micrographs show a good infiltration quality and interfacial bonding between both phases. An increase in Young's modulus of 28 % and compressive strength in the MMC can be achieved compared to the AlSi12-matrix.

Highly conductive diamond skeleton reinforced Cu-matrix composites for high-efficiency thermal management

The weak interfacial bonding strength between diamond and copper intrinsically restricts the enhancement of the thermal conductivity of diamond particles/copper composites (abbreviated as DP/Cu). This work first proposed the diamond skeleton (DS) as the reinforcement element rather than dispersed diamond particles. The tungsten (W) transition layer (c.a. ∼300 nm thick) having adequate thermal expansion coefficient was sputtered onto the surface of DS via vacuum evaporation technology, aiming to improve the wettability between diamond and copper and accordingly increase the thermal conductivity of DS/copper composites extruded by gas pressure infiltration technique. The experimental results show that the coated W layer can effectively improve the wettability of the diamond surface and reduce the wettability angle from 108.6° to 13.2°. Raman and XRD spectra show that the W layer can, to a great extent, prevent the graphitization of the diamond surface. SEM and EDX evidence a continuous heat transfer path of DS inside the composites. The thermal conductivity of the DS/Cu composite with low diamond loading of 18.4 vol% reaches 575 W/mK, 43.3% higher than that of pure Cu. Finite element simulations show that DS exhibits excellent heat transfer characteristics, agreeing well with the thermal conductivity simulation results.

Aluminium Matrix Composite Materials Reinforced by 3D-Printed Ceramic Preforms.

This article employed the fused deposition modelling (FDM) method and gas-pressure infiltration to manufacture alumina/AlSi12 composites. Porous ceramic skeletons were prepared by FDM 3D printing of two different alumina powder-filed filaments. The organic component was removed using a combination of solvent and heat debinding, and the materials were then sintered at 1500 °C to complete the process. Thermogravimetric tests and DTA analysis were performed to develop an appropriate degradation and sintering program. Manufactured skeletons were subjected to microstructure analysis, porosity analysis, and bending test. The sintering process produced porous alumina ceramic samples with no residual carbon content. Open porosity could occur due to the binder's degradation. Liquid metal was infiltrated into the ceramic, efficiently filling any open pores and forming a three-dimensional network of the aluminium phase. The microstructure and characteristics of the fabricated materials were investigated using high-resolution scanning electron microscopy, computer tomography, hardness testing, and bending strength testing. The developed composite materials are characterized by the required structure-low porosity and homogenous distribution of the reinforcing phase, better mechanical properties than their matrix and more than twice as high hardness. Hence, the developed innovative technology of their manufacturing can be used in practice.

Influence of Melt Infiltration Parameters on Structural and Mechanical Properties of Al-4.3wt.%Cu-EP Syntactic Foam

The present research concerns fabrication of Al-4.3wt.%Cu metal syntactic foams using expanded perlite particles (EPPs). A gas pressure infiltration technique was employed to fabricate the aluminium syntactic foams under different infiltration temperatures and pressures. Ambient air pressure and 750 °C were identified as the favoured processing conditions for full infiltration of the melt. The average density and EP volume percentage of the fabricated foams were measured to be about 1.55 g/cm3 and 50.3%, respectively. Melt infiltration is believed to be mainly controlled by the breakage of the aluminium oxide layer on the melt surface and melt viscosity. Preferential infiltration of the melt between the mould wall and the EP particles bed complemented by radial melt infiltration toward the centre of the samples was identified. The effects of EP particles on growth of the nucleated primary α-aluminium phase were discussed. XRD and EDS analyses suggested some chemical reactions at the interface of EPPs with the molten aluminium. T6 heat treatment in the ambient atmosphere improved the average compressive tensile strength, plateau stress, and absorption capacity of the syntactic foams by more than 100%. Uniform deformation and similar densification strains (about 40%) of the as-fabricated and heat-treated syntactic foams during the compression test suggested uniform distribution of EP particles and metallic struts in the aluminium alloy matrix.

In-situ SEM investigation on the damage behavior of an interpenetrating metal ceramic composite

For the investigation of interpenetrating materials, the microstructure and the associated damage mechanism are crucial for the understanding of its properties. In this work, an aluminum-alumina interpenetrating composite is investigated and characterized regarding the microstructure and the tensile and compression properties during in-situ SEM experiments. The composite is fabricated by gas pressure infiltration and consists of a highly homogeneous and fine-pored Al2O3 preform and an AlSi10Mg cast alloy. Due to the fine-pored ceramic phase, building a strong contrast to the metallic phase, digital image correlation (DIC) could be applied directly on the SEM images, captured during the in-situ experiments, without the need of a speckle pattern on the surface. The microstructure analysis and DIC results were correlated with the load level, derived from stress-strain curves, to achieve deeper understanding from the damage behavior in interpenetrating metal ceramic composites.

Assessment of Two Advanced Aluminium-Based Metal Matrix Composites for Application to High Energy Physics Detectors

The Outer Tracker of the Compact Muon Solenoid (CMS), one of the large experiments at the CERN Large Hadron Collider, will consist of about 13,200 modules, each built up of two silicon sensors. The modules and support structures include thousands of parts that contribute to positioning and cooling the sensors during operation at -30 °C. These parts should be low mass while featuring high thermal conductivity, stiffness and strength. Their thermal expansion coefficient should match that of silicon to avoid deformations during cooling cycles. Due to their unique thermal and mechanical properties, aluminium-carbon fibre (Al/Cf) Metal Matrix Composites are the material of choice to produce such light and stable thermal management components for High Energy Physics detectors. For the CMS Outer Tracker, about 500,000 cm3 of Al/Cf raw material will be required to be produced through a reliable process to guarantee consistent properties throughout parts manufacturing. Two Al/Cf production routes are currently considered: liquid casting by gas-pressure infiltration and a powder metallurgy process based on continuous semi-liquid phase sintering. The dimensional stability of the resulting material is of paramount importance. Irreversible change of shape may be induced by moisture adsorption and the onset of galvanic corrosion at the discontinuous interfaces between Cf and Al. This paper presents the results of an extensive investigation through Computed Microtomography, direct microscopical investigations, analysis of the interfaces and metrology measurements aimed at comparing and interpreting the response to different environments of the respective products. The results obtained confirm the suitability of the two investigated Al/Cf MMCs for application to components of the CMS Outer Tracker, requiring tight geometrical control and microstructural stability over time. However, for PM parts sintered through the semi-liquid phase process, a multilayered protective noble metal coating is necessary the make them impervious to moisture, allowing dimensional stability to be guaranteed and the onset of corrosion phenomena to be avoided, while the product obtained by gas-pressure infiltration has shown less sensitive even to extreme temperature-humidity cycles and may be used uncoated.

Effect of Temperature on the Complex Modulus of Mg-Based Unidirectionally Aligned Carbon Fiber Composites.

Composite materials based on magnesium-lithium (MgLi) and magnesium-yttrium (MgY) matrices reinforced with unidirectional carbon fibers were prepared using the gas pressure infiltration method. Two types of carbon fibers were used, high-strength PAN-based T300 fibers and high-modulus pitch-based Granoc fibers. The PAN-based carbon fibers have an internal turbostratic structure composed of crystallites. The pitch-based carbon fibers have a longitudinally aligned graphite crystal structure. The internal carbon fiber structure is crucial in the context of the interfacial reaction with the alloying element. There are various mechanisms of bonding to carbon fibers in the case of magnesium-lithium and magnesium-yttrium alloys. This paper presents the use of the DMA method for the characterization of the role of alloying elements in the quality of interfacial bonding and the influence on the complex modulus at increasingly elevated temperatures (50-250 °C). The complex modulus values of the composites with T300 fibers were in the range of 118-136 GPa. The complex modulus values of the composites with Granoc fibers were in the range of 198-236 GPa. The damping capacity of magnesium-based unidirectionally aligned carbon fiber composites is related to the quality of the interfacial bonding.

Gradient interface formation in Cu–Cr/diamond(Ti) composites prepared by gas pressure infiltration

Interface design is critical to enhance thermal properties of Cu/diamond composite as a promising thermal management material. Herein we combine Cr alloying in Cu matrix with Ti coating on diamond particles to prepare a Cu-0.5 wt%Cr/diamond(Ti) composite in an attempt to construct a TiC/Cr3C2 gradient interface to improve phonon transfer at the interface. The Ti-coating on diamond particles transforms to a TiC layer during deposition. As the TiC layer is 20 nm thick, a part of Cr atoms in the Cu matrix diffuse through the TiC layer to react with the C atoms on diamond particles to form a 30 nm-thick Cr3C2 layer, and a 28 nm-thick graphite layer is generated on diamond particle surface. With increasing the TiC layer thickness to 80 nm, a small part of Cr atoms can still pass through the TiC layer to form discrete chromium carbide particles and a 20 nm-thick graphite layer is generated. The interfacial structure of the Cu-0.5 wt%Cr/diamond(Ti) composite is characterized as diamond/graphite/TiC/Cr3C2/Cu, and the thermal conductivity for the Cu-0.5 wt%Cr/diamond(Ti) composite has a 549 W m−1 K−1 value lower than the 735 W m−1 K−1 value for the Cu/diamond(Ti) composite. The lowered thermal conductivity is attributed to the formed graphite layer and the thick Cr3C2 layer in the Cu–Cr/diamond(Ti) composite. This study provides guidance for designing and tailoring gradient interface for efficient phonon transport in Cu/diamond composites.

TEM Study of the Microstructure of an Alumina/Al Composite Prepared by Gas-Pressure Infiltration.

Ceramic injection moulding and gas-pressure infiltration were employed for the manufacturing of alumina/AlSi10Mg composites. Porous ceramic preforms were prepared by mixing alumina powder with a multi-binder system and injection moulding the powder polymer slurry. Then, the organic part was removed through a combination of solvent and thermal debinding, and, finally, the materials were sintered at different temperatures. Degrading the binder enabled open canals to form. The sintering process created a porous ceramic material consisting of alumina without any residual carbon content. During infiltration, the liquid metal filled the empty spaces (pores) effectively and formed a three-dimensional network of metal in the ceramic. The microstructure and properties of the manufactured materials were examined using high-resolution transmission electron microscopy, porosimetry, and bending strength testing. Microscopy observations showed that the fabricated composite materials are characterised by a percolation type of microstructure and a lack of unfilled pores. The research confirmed the diversified nature of the connection at the particle–matrix interface. It was observed that the interphase boundary was characterised by the lack of a transition zone between the components or a continuous transition zone, with the thickness not exceeding 30 nm. Thanks to their increased mechanical properties and low density, the obtained composites could be used in the automotive industry as a material for small piston rings and rods, connecting rods, or even gears.

Effect of interface structure on thermal conductivity and stability of diamond/aluminum composites

Diamond/aluminum composites were fabricated by gas pressure infiltration with pure aluminum and pristine diamond, nanoscale W or WC coated diamond as raw materials. The influence of interfacial phase type and size on the thermal conductivity of the composites was investigated. The evolution of microstructure and properties of composites under temperature shock environment was also analyzed. The introduction of W and WC coatings inhibits the formation of interfacial phase Al4C3, while the generation of amorphous carbon in WC-coated diamond/aluminum composite causes a weak interface bonding and huge acoustic impedance difference with diamond, leading to a decrease in thermal conductivity. The W-coated diamond/aluminum composite shows the optimal thermal properties after 1000 cycles of temperature shock treatment. The introduction of W coating can improve performance stability while maintaining high thermal conductivity, making them promising thermal management composites.

Unveiling interfacial structure and improving thermal conductivity of Cu/diamond composites reinforced with Zr-coated diamond particles

To overcome the drawback of weak interface bonding in diamond particles reinforced Cu matrix (Cu/diamond) composites, we prepared the Cu/Zr-diamond composites via a gas pressure infiltration method with Zr coatings with thicknesses from 47 nm to 430 nm on diamond surfaces. The scanning transmission electron microscopy (STEM) and X-ray diffraction (XRD) analyses reveal that during preparation the gradual transformation of metallic Zr to ZrC occurs through the diffusion of C atoms, and the crystallographic orientation relationship between diamond and ZrC is characterized as (1¯11)diamond//(1¯11)ZrC and [110]diamond//[110]ZrC. The formed ZrC layer between diamond and Cu can bridge the large gap of acoustic impedance and greatly strengthen the interface bonding, and a maximal thermal conductivity of 735 W m−1 K−1 is achieved with the thickness of the interfacial ZrC layer of 50 nm (corresponding to Zr-coating thickness of 47 nm). However, with increasing the thickness of the interfacial ZrC layer, the composite thermal conductivity decreases attributed to the intrinsic low thermal conductivity of ZrC and the interface de-bonding with the large ZrC layer thickness. This study accurately establishes the relationship between interfacial structure and thermal conductivity and provides guidance for the interface design in Cu/diamond composites.

3D modeling and experimental investigation on the damage behavior of an interpenetrating metal ceramic composite (IMCC) under compression

In this study, an interpenetrating metal–ceramic composite, manufactured via gas pressure infiltration of AlSi10Mg into an open porous alumina foam is investigated three dimensionally on its damage behavior under compression. Experimentally, compression tests as well as in-situ computed X-ray tomography experiments with digital volume correlation evaluation were carried out. Numerically, the reconstructed microstructure of the interpenetrating metal–ceramic composite was modeled and compression tests were simulated via FEM simulation, to investigate the microstructural damage onset and failure behavior. Three stages of failure could be observed, which are described in detail on microstructural as well as macroscopic level. Additionally, a comparison between simulation and experiment is made, correlations are elaborated and observed differences discussed.

Uniaxial Compressive Behavior of AA5083/SiC Co-Continuous Ceramic Composite Fabricated by Gas Pressure Infiltration for Armour Applications

A novel approach of a gas pressure infiltration technique is presented for the synthesis of Co-Continuous Ceramic Composite (C4). SiC foams of varying pore sizes were infiltrated with aluminium AA5083. Optical examination revealed that the SiC foams contained open cells with a network of triangular voids. The number of pores-per-inch (PPI) in the foams was found to depend on the strut thickness and pore diameter. The compressive strengths of two foam configurations, 10 and 20 PPI, were estimated to lie between 1–2 MPa. After infiltration, the compressive yield strength of the resulting C4 was observed to increase to 126 MPa and 120 MPa, respectively, for the 10 and 20 PPI C4. Additionally, the infiltration of ceramic foam with the AA5083 alloy resulted in an increase in strength of 58–100 times when compared with plain ceramic foam. The failure modes of the composites in compression were analyzed by crack propagation and determining the type of failure. The study revealed that shear failure and vertical splitting were the predominant mechanisms of compression failure, and that the fabricated C4 is advantageous in mechanical properties compared to the plain ceramic foam. This study, therefore, suggests the use of C4 composites in armour applications.

Metal/Graphite flakes foams for heat sink applications

Materials combining a certain degree of macroporosity and high thermal conductivity are interesting for current active thermal management applications. In this work a new class of multiphase composite porous materials have been fabricated. The materials are inspired by a recently developed family of high thermally conductive composite materials formed by combination of graphite flakes, ceramic particles and a metal matrix. Replacing the ceramic particles by NaCl particles allow obtaining an interconnected pore structure in the material after dissolution in water. Materials with aluminum matrices have been obtained by gas pressure infiltration of preforms conformed by mixtures of graphite flakes and NaCl particles. The thermal conductivity has been calculated and experimental results are discussed in accordance with two mathematical models based on ideal microstructures: i) alternated layers of semi-infinite continuous graphite flakes and metallic foam, and ii) a metallic foam with oriented graphite flakes in the struts.

Push-Out Method for Micro Measurements of Interfacial Strength in Aluminium Alloy Matrix Composites.

The main goal of this work was the evaluation of the interfacial strength of the carbon fibres/aluminium matrix interface dependently on the utilised composite fabrication method, namely high pressure die casting and gas pressure infiltration. In addition, the influence of a Ni-P coating on the C-fibres was investigated. The proposed measurements of the interfacial strength were carried out by means of the “push-out” method. The interfacial strength of the samples fabricated using the high-pressure infiltration method average between 19.03 MPa and 45.34 MPa.

Manufacturing and Investigation of In Situ and Ex Situ Produced Aluminum Matrix Foam‐Filled Tubes

Composite metal foams (CMFs) are hybrid structures, which are usually produced from separate parts, and not in one step as functional, structural elements. Functional CMFs are characterized by high strength, high stiffness, and extreme energy absorbing properties compared with conventional metallic foams, which allow them to be used as load‐bearing and energy absorbing elements. Test specimens are made in AlMgSi0.5 tubes with the wall thickness of 5 mm. AlSi12 casting alloy is used as matrix material. To ensure the foam structure porosity, lightweight expanded clay aggregate particles (LECAPs) are used with unimodal and bimodal size distribution. The results show that low‐cost unimodal and bimodal foam‐filled tubes (FFTs) can be produced in situ by inert gas pressure infiltration. Besides their low density, these CMFs achieve high strength, high toughness, and special, functional properties compared with simple metallic foams. After heat treatment, in situ produced bimodal FFTs have the highest energy absorption capacity of an average of 67.2 J cm−3, which is 9% higher than the average value of the ex situ FFTs. Therefore, it is advantageous to produce in situ FFTs, because with proper manufacturing, it requires less machining, making the production easier, while achieving better compressive properties.

Enhanced wetting and properties of Carbon/Copper composites by Cu-Fe alloying

ABSTRACT Using Fe reaction products to overcome the poor wettability between copper and carbon, C/Cu-Fe composites with excellent properties were prepared by gas pressure infiltration technique. The elemental Fe, being distributed between carbon and Cu, reacted with carbon to form Fe3C layer and effectively improved the wettability of the C/Cu system. The contact angle decreased from 124° to 21°. Compared to composites without Fe doping, the C/Cu-Fe composites exhibit significantly higher compressive and flexural strengths, as well as electrical resistivity reaching six times better than the industry standard requirement. Microstructure analysis indicates that the continuous tight Fe3C interlayer with moderate thickness at the C/Cu interface has a bridge effect on the interfacial bonding enhancement.

2D and 3D in-situ mechanical testing of an interpenetrating metal ceramic composite consisting of a slurry-based ceramic foam and AlSi10Mg

An interpenetrating metal ceramic composite, based on a ceramic foam and an AlSi10Mg light-weight aluminum alloy, is investigated under compressive load. The ceramic preform is produced by mechanical stirring, drying and finally sintering. It has a relative density of approximately 25% and is infiltrated via gas-pressure infiltration with the aluminum alloy. The damage processes during compressive load, as well as an understanding of crack development is in focus of this research and obtained by complementing 2D and 3D characterization methods. Therefore, a 2D surface in-situ investigation setup with an universal testing machine, a digital image correlation and a microscopy setup is used. For 3D investigation, a compression test with an in-situ X-ray computed tomography is developed and carried out to get an understanding of the material crack growth and crack propagation, as well as its failure mechanisms inside the interpenetrating metal-ceramic phase composite. The material shows crack initiations in the ceramic phase parallel to the load direction. Formation of crack clusters is followed then by a change in failure mechanism due to shear stress dominated failure with a macroscopic crack in 45° regarding the load direction. A good-natured failure of the composite could be determined. The combination of the 2D and 3D investigation methods gives an insight into the failure behavior of the interpenetrating composite and thus contributes to the understanding of the failure mechanism beyond the current state of knowledge.