Gas Pressure Infiltration Research Articles

Fabrication of Co-Continuous ceramic composite (C4) through gas pressure infiltration technique

Co-Continuous Ceramic Composites (C4) have been fabricated through gas pressure infiltration technique with SiC foam reinforcement of 10PPI and 20PPI, and with AA5083 alloy as matrix. The fabricated composites (C4) were tested for mechanical properties at static condition. This study delineates the effect of pores per inch (PPI) of SiC foams on the mechanical properties of the composite. The 10PPI C4 composite with highest content of AA5083 (81%) exhibited a compressive strength of 131 MPa, 5% greater than 20PPI C4 composite. The C4 composite displayed 65 times higher compressive strength than SiC foam (~2 MPa). The compression failure mode was found to be shear failure and vertical splitting, with the SiC foam failing first,followed by failure of AA5083. A positive correlation was observed between the compressive strength and hardness of the composite, where 10PPI composite exhibits 56 BHN, and 20PPI with 50 BHN. Additionally, microstructural analysis was performed to characterize the interface morphology of SiC foam and AA5083 alloy.

First-principles calculation of diamond/Al interface properties and study of interface reaction

First-principles calculation and experimental methods are used to study the interfacial properties and reaction of diamond/Al composites. Based on the first-principles method, the interfacial adhesion work (<i>W</i><sub>ad</sub>), electronic structure and charge transfer of diamond/Al models are calculated systematically. The results show that the adhesion work of diamond(100)/Al(111) is 41% higher than that of diamond(111)/Al(111), therefore, the interface bonding of diamond(100)/Al(111) interface is stronger. According to the analysis of the electronic structure, there are more charges transferring at the diamond(100)/Al(111) interface, and the high charge density is distributed on the side of C atoms. The redistribution of charges at the interface is conducive to the formation of Al—C bond, so that the tendency of forming Al—C bonds is greater. The introduction of Al—C bond can promote the formation of C—C bond at the diamond(100)/Al(111) interface and improve the interfacial adhesion work. In addition, the diamond/Al composites are fabricated by vacuum gas pressure infiltration, and multi-scale characterization of the interface structure of diamond/Al composites is carried out. The interfacial debonding occurs mainly on the diamond {111}. Meanwhile, the interface product Al<sub>4</sub>C<sub>3</sub> is easier to form on the diamond {100}. The experimental phenomenon is consistent with the calculated results. Moreover, the influence of the interfacial reaction on the properties and stability of diamond/Al composites are further discussed through heat-moisture treatment. The study finds that the performance degradation in heat-moisture environment is related mainly to the hydrolysis of the interface product Al<sub>4</sub>C<sub>3</sub>. After 60 days’ heat-moisture, the thermal conductivity of the diamond/Al composites decreases by 29.9%, and the bending strength is reduced by 40.1%. The large attenuation of performance is not conducive to the stability of composites in complex environments. Therefore, inhibiting the formation of Al<sub>4</sub>C<sub>3</sub> and improving interfacial selectivity are of great importance in developing the performance and stability of diamond/Al composites. The research in this paper not only lays a theoretical foundation for the first-principles calculation of the interface properties of diamond/metal, but also possesses important guidance significance in designing the diamond/metal composites.

High thermal conductivity and low thermal expansion coefficient of isotropic graphite-reinforced aluminum matrix composites prepared by in situ curing of silicon aerogel

In this study, graphite with different weight fraction of copper plating was obtained through electroless coating, then a new way called in situ curing of silicon aerogel was introduced to fabricate the preform of graphite-reinforced metal matrix composites, which has the advantages of short production cycle, low energy consumption, high mechanical strength, uniform pore distribution, and near net size formation, followed by aluminum impregnation through vacuum gas pressure infiltration. The obtained results prove that the composites made of copper-coated graphite have isotropic high thermal conductivity and low coefficient of thermal efficiency, with machinability and low density determined by raw materials making them competitive in the related fields.

Numerical and Experimental Characterization of Elastic Properties of a Novel, Highly Homogeneous Interpenetrating Metal Ceramic Composite

An interpenetrating aluminum–alumina composite is presented, based on a ceramic foam manufactured via a novel slurry‐based route resulting in a highly homogeneous preform microstructure in contrast to other preform techniques. The metal matrix composite (MMC) is produced by infiltrating the open‐porous ceramic preform with molten aluminum at 700 °C using a Argon‐driven gas pressure infiltration process. The resulting MMC and the primary ceramic foam are investigated both numerically and experimentally in terms of microstructural characteristics. In addition, the mechanical behavior of the material as well as the structural and material interactions on the microscale are investigated. To characterize the MMC regarding mechanical isotropy, elastic properties are determined experimentally via ultrasonic phase spectroscopy (UPS). A fast Fourier transform (FFT) formulation is used to simulate the complex 3D microstructure with reasonable effort based on image‐data gathered from high‐resolution X‐ray computed tomography (CT) scans of the ceramic foam as computational grid. Simulations prove that the material properties are, indeed, considered as highly homogeneous with respect to the material microstructure. A comparison with effective experimental investigations confirms these findings.

Mechanical Properties of Cu-B/Diamond Composites Prepared by Gas Pressure Infiltration

Diamond particles reinforced boron-alloyed Cu matrix (Cu-xB/diamond, x = 0.1, 0.2, 0.3, 0.4, 0.5, and 1.0 wt.%) composites were prepared by gas pressure infiltration. The size of the diamond particles was ~ 230 μm and the diamond volume fraction in the composites was ~ 66%. The interfacial carbide evolution plays an important role in improving the interfacial bonding and enhancing the mechanical properties of the Cu-B/diamond composites. The tensile, compressive and bending strengths firstly increase and then decrease with increasing boron content, giving a maximum tensile strength of 204 MPa, a maximum compressive strength of 608 MPa, and a maximum bending strength of 513 MPa at 0.5 wt.% B addition. The monotonic uniaxial tensile stress–strain curves of the Cu-B/diamond composites were predicted by using the Mori–Tanaka, generalized self-consistent, and Torquato identical hard spheres approximation models. The results suggest that alloying B to Cu matrix is an effective route to strengthening Cu/diamond composites.

High-Temperature Thermal Conductivity and Thermal Cycling Behavior of Cu–B/Diamond Composites

Diamond particle-reinforced copper matrix (Cu/diamond) composites are currently considered as a promising thermal management material due to their high thermal conductivity and matching coefficient of thermal expansion (CTE) with the semiconductor. In this article, the Cu– <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$x\text{B}$ </tex-math></inline-formula> /diamond ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$x = 0.1$ </tex-math></inline-formula> –1.0 wt%) composites with 67% diamond volume fraction were produced by gas-pressure infiltration. The thermal conductivity of the Cu–B/diamond composites decreases with the increasing temperature from 323 to 673 K, owing to the property change of the composite components. The samples were subjected to 100 thermal cycles from 218 to 423 K to investigate the long-term stability of the Cu–B/diamond composites. The results suggest that the interface structure evolution plays a critical role in determining the high-temperature thermal conductivity and thermal cycling behavior of the Cu–B/diamond composites. By measuring the thermal properties before and after thermal cycling, we found that the Cu–0.5wt%B/diamond composite has the best thermal stability. After 100 thermal cycles, the room temperature thermal conductivity remains almost unchanged at ~740 W/mK, and the CTE increases slightly from 4.88 to 4.97 ppm/K. This article expands the understanding of the thermal properties of the Cu-B/diamond composites and provides a fundamental basis for their electronics packaging applications.

Highly Adsorptive and Magneto-Inductive Guefoams (Multifunctional Guest-Containing Foams) For Enhanced Energy-Efficient Preconcentration and Management of VOCs.

The design of multifunctional materials is a current demand for high-end technological applications that need to combine different functions unable to be accomplished by a single material. The aim of this work is to present, at first glance, a new family of recently patented multifunctional porous materials developed by locating granular phases with specific functionality (guests) within the cavities of open-pore cellular materials (hosts) and, at second glance, the use of a set of these materials for the preconcentration and management of volatile organic compounds (VOCs). These materials (herein known as Guefoams, acronym for Guest-containing foams), present host foams and guest phases that are not bonded and therefore allow fluids to pass through. The processing method is the gas pressure infiltration of a host precursor into preforms containing particulate guest phases covered by a NaCl martyr coating, which is later dissolved in water. The manuscript shows the manufacture and characterization of a specific set of Guefoams composed of aluminum foams that incorporate both steel particles and activated carbon particles as guest phases into the same material. These guest phases make the materials highly adsorbent and susceptible to rapid desorption by magnetic induction, two properties never achieved with traditional foams that transform these materials into perfect candidates for preconcentration and energy-efficient management of VOCs. The manuscript concludes with a discussion on advisible properties to consider when exploring the use of these materials in the mentioned applications.

Enhanced Thermal Conductivity and Bending Strength of Graphite Flakes/aluminum Composites Via Graphite Surface Modification

The effect of graphite surface modification on the thermal conductivity (TC) and bending strength of graphite flakes /Al composites (Gf/Al) prepared by gas pressure infiltration were investigated. Al3Ni and Al4C3 phase may form at the interface in Ni-coated Gf/Al and uncoated Gf/Al composites, respectively, while the Al-Cu compound cannot be observed in Cu-coated Gf/Al composites. The Cu and Ni coatings enhance TC and the bending strength of the composites in the meantime. TC of Cu-coated Gf/Al composites reach 515 Wm−1·K−1 with 75 vol% Gf, which are higher than that of Ni-coated Gf/Al. Meanwhile, due to Al3Ni at the interface, the bending strength of Ni-coated Gf/Al composites are far more than those of the uncoated and Cu-coated Gf/Al with the same content of Gf. The results indicate that metal-coated Gf can effectively improve the interfacial bonding between Gf and Al.

High volume fraction of copper coated graphite flake∖Nitrogen doped carbon fiber reinforced aluminum matrix composites

High volume fraction of carbon material reinforced aluminum matrix composites were developed by optimized vacuum gas pressure infiltration method, among which the reinforced materials are graphite flake and carbon fiber. To enhance the wettability between the reinforments and aluminum matrix, graphite flake was coated with a thin layer of copper by electroless plating and CF was doped with nitrogen, which proves to be effective and efficient. With the increase of reinforcements from 50 to 80 vol%, the flexural strength of the composites remains at practical level; the coefficients of thermal expansion decrease under the same temperature in direction parallel to basal planes of graphite flake; the thermal conductivity of the composites increase from 327 to 402 W/m K, adding up to relatively high comprehensive performances.

Interfacial products and thermal conductivity of diamond/Al composites reinforced with ZrC-coated diamond particles

The Al4C3-containing diamond/Al composites encounter a severe hydrolysis problem in moist environment. A 450 nm thick Zr layer was coated onto diamond particles by magnetron sputtering and was transformed to ZrC layer by subsequent heat treatment at 1050 °C. The ZrC-coated diamond particles were then incorporated into Al matrix to prepare diamond(ZrC)/Al composite by gas pressure infiltration. Although Al4C3 is still formed outside the ZrC layer in the diamond(ZrC)/Al composite, the amount of Al4C3 is greatly reduced compared with the unmodified diamond/Al composite. The thermal conductivity declines from 709 W/mK for the unmodified diamond/Al composite to 572 W/mK for the diamond(ZrC)/Al composite, which is attributed to the intrinsically low thermal conductivity of the ZrC layer. This work suggests an optional way of reducing undesirable hydrolytic Al4C3 but maintaining acceptable thermal conductivity in diamond/Al composites by coating ZrC layer onto diamond particles.

Construction of 3D interconnected diamond networks in Al-matrix composite for high-efficiency thermal management

Realizing high-efficiency thermal management is of great significance for the fast growth of high-performance electronic devices. Herein, three-dimensional (3D) diamond networks (DN) are proposed as highly thermal conductive reinforcements for Al-matrix composite by template-directed chemical vapor deposition (CVD) on Cr-modified Cu foams. The diamond networks with dense and uniform structure were further incorporated with pure Al by gas pressure infiltration (GPI). Results showed that the diamond skeletons were uniformly and integrally distributed in the dense Al matrix with a compact interfacial bonding and limited interface product after GPI process. A relatively high thermal conductivity of 315.7 W/mK was achieved at a low diamond loading of 4.6 vol.%, which was equivalent to 54% enhancement compared to pure Al. The synthesized diamond networks with high quality and continuous structure can act as high-efficiency heat transfer pathways to ensure most of heat being transferred through the 3D diamond skeletons, which effectively reduced the phonon-boundary scatterings. As a consequence, the fabricated composite shows a great superiority in both thermal conductivity and thermal conductivity enhancement efficiency as compared with the conventional Al-matrix composites reinforced with even higher volume fraction of diamond particles. The construction of 3D interconnected diamond networks in metal-matrix composites might open new doors for the design and preparation of high-efficiency thermal management materials.

Tunable coefficient of thermal expansion of Cu-B/diamond composites prepared by gas pressure infiltration

Cu-B matrix composites reinforced with diamond particles (Cu-B/diamond) were prepared by gas pressure infiltration (GPI). The effect of boron addition in the range of 0–1.0 wt% on the thermal expansion behavior of the Cu-B/diamond composites was evaluated. The coefficient of thermal expansion (CTE) of the Cu-B/diamond composites initially decreases and then increases with increasing boron content. The minimum CTE value of 4.88 × 10−6/K is obtained at 0.5 wt% B addition, which satisfies the requirement of CTE of semiconductors (range of 4–8 × 10−6/K) for electronic packaging applications. The variation of CTE of the Cu-B/diamond composites is attributed to the formation of interfacial carbides and their morphological evolution. The interface structure evolves from discrete triangular carbides into continuous carbide layer with increasing boron content. The increase in the quantity of discrete carbides enhances the interface, but the formation of continuous carbides impairs the interfacial bonding of the Cu-B/diamond composites. The results suggest that alloying B to Cu matrix is an effective route to tune the coefficient of thermal expansion of Cu/diamond composites.

Investigation of wear and corrosion behavior of graphene nanoplatelet-coated B4C reinforced Al–Si matrix semi-ceramic hybrid composites

The present study aims to produce graphene nanoplatelet-coated B4C ceramic particle using semi-powder method and to investigate the effect of graphene nanoplatelets on wear and corrosion performance of Al–Si-based metal matrix hybrid composites. For this purpose, first graphene nanoplatelets at different ratios (0.25, 0.5, and 1 vol.%) were coated to the surfaces of B4C particles and then the Al–Si alloy was infiltrated into the reinforcements by gas pressure infiltration method. The characterization of graphene nanoplatelet-coated B4C powders and its composites was carried out by X-ray diffraction, differential scanning calorimetry, scanning electron microscope, and transmission electron microscope analysis. Tribological properties were investigated by reciprocating ball-on-flat method under three different loads (10–20–40 N) in a dry environment. The corrosion resistance was carried out with Tafel polarization method in 3.5% NaCl solution. Characterization results show that graphene coated on the B4C surface was successfully achieved by semi-powder method. After infiltration process, a new phase formation was not observed, but porosity increased with the increase of graphene content. When the boron carbide surface was coated with 0.5vol.% graphene, it was determined that the specific wear resistance increased by 55% and the corrosion resistance decreased by 12%.

Microstructure and thermal stability of the Cu-ZrB2 and CuCr1Zr-ZrB2 composites prepared by gas pressure infiltration

Microstructure and thermal stability of the Cu-ZrB2 and CuCr1Zr-ZrB2 composites prepared by gas pressure infiltration

Microstructure and thermal properties of Cr7C3 coated graphite flakes/Al composites

Graphite flakes (Gf) were coated with Cr7C3 by salt bathing coating, and the Cr7C3 coated Gf reinforced Al matrix composites were prepared by gas pressure infiltration. Surface morphology of uncoated and Cr7C3 coated Gf, the interfacial characteristics of Cr7C3 coated Gf/Al composites were observed by SEM. Surface of Cr7C3 coated Gf is smooth without defects, the Cr7C3 coating effectively improved the wettability. When volume fraction of Gf is below 50%, the experimental value of thermal conductivity (TC) is basically consistent with the calculated value of the EMA model. When volume fraction of Gf is over 50%, the growth of deviates from the EMA model curve. Coefficient of thermal expansion (CTE) of composite was predicted by Kerner model and Orientation Disc model, because Kerner model does not consider the anisotropy of Gf and inaccurately predict the change of CTE. However, the Orientation Disc model can predict the change of CTE better, but there is certainly deviation.

Effect of chromium coated carbon fiber on the thermal and mechanical properties of Cr@Gf/Cr@CF/Al composites

In order to obtain composites which can meet the requirements of current thermal management materials, a new family of ternary aluminum matrix composites has been recently developed through vacuum gas pressure infiltration. Carbon fiber (CF) and graphite flake are both used in the composites as reinforcements, among which CF plays a role in strengthening the aluminum matrix and graphite flake plays a role in enhancing the thermal conductivity (TC) of the composites. Both of them were coated with chromium uniformly using salt bath coating to improve the wettability between the matrix and reinforcement, which were proved by the micro-structural characterization. The effects of different volume of chromium coated CF on the thermal–physical properties and mechanical properties of the composites were investigated, from which we could conclude that CF could not only dramatically increase the mechanical properties of the composites, but also can space apart the graphite flake layers for infiltration. What’s more, a Fricke prediction model was adapted to estimate the TC of the composites, and the reasons of the gap between the measured value and prediction model were systematically analyzed.

Internal load transfer in an interpenetrating metal/ceramic composite material studied using energy dispersive synchrotron X-ray diffraction

The mechanism of internal load transfer in a newly developed interpenetrating metal/ceramic composite is studied for the first time in this work using energy dispersive synchrotron X-ray diffraction. The composite was fabricated by infiltration of Al12Si melt in an open porous alumina preform, fabricated using a mixture of two different polymer waxes as pore formers, by gas pressure infiltration. Several diffraction planes of all three crystalline phases of the composite – alumina, silicon and aluminum solid solution are investigated. Lattice strains, both along and transverse to the loading direction, in each phase are calculated from the shifts in the measured diffraction peak positions. Results show that until about 100 MPa applied compressive stress, all three phases undergo elastic deformation. At higher applied stresses aluminum undergoes plastic deformation and correspondingly load is transferred to alumina. The load carrying capability of alumina is however limited by incipient damage in this phase. At applied compressive stresses higher than 187 MPa, load carried by the alumina phase continuously decreases and correspondingly more load is again carried by the aluminum solid solution. Throughout, the fraction of load carried by silicon remains almost constant, suggesting no significant load transfer within the metallic alloy itself.

Developing high-performance laminated Cu/TiC composites through melt infiltration of Ni-doped freeze-cast preforms

Abstract Nacre-inspired laminated composites have been proven to possess a unique combination of strength and toughness. In this study, we fabricated nacre-mimetic Cu/TiC composites via unidirectional freezing of aqueous TiC slurries containing different amounts of NiO additives, followed by ice sublimation, carbothermal reduction of NiO to Ni during sintering and then gas-pressure infiltration of the Cu melt. The introduction of Ni greatly facilitated the densification of ceramic lamellae and enhanced the interfacial bonding between Cu and TiC. The resultant composites displayed outstanding damage tolerance and anisotropic electrical conductivities. Specifically, for an ∼31 vol% TiC–Cu composite containing 24 wt% Ni in the ceramic lamellae (based on the TiC content), a fracture toughness (KJc) of 72.5 ± 1.0 MPa·m1/2, work of fracture of 53.4 ± 3.5 kJ/m2, bending strength of 725 ± 11 MPa and longitudinal electrical conductivity of 22.7 MS/m (∼60% of the Cu matrix) were achieved, which were approx. 81%, 536%, 122% and 97% higher than those of the Ni-free composite, respectively. Noticeable toughening was demonstrated to be a consequence of multiple cracking, plastic deformation and uncracked-ligament bridging of the metal layers, as well as crack deflection and blunting. On the other hand, significant strengthening resulted from tailoring the microstructures in the ceramic layers and at the Cu/TiC interface as a result of Ni doping. We believe that the facile strategy adopted herein provides an effective way to solve the problems of wetting and bonding related to metal infiltration and can be readily extended to the preparation of other nacre-inspired metal−ceramic composites.

Modeling of the mechanical and physical properties of hybrid composites produced by gas pressure infiltration

In this study, mechanical and physical properties of hybrid composites were analyzed by using a data acquisition technique like artificial neural networks. Matlab software was used to examine the effects of test parameters on infiltration temperature and pressure. Bending strength, hardness and density of hybrid composite were affected in neural network training and test. Firstly, training set was prepared for the MMCs. In this set, three various training algorithms were used with artificial neural network. At the end of the each learning, the accuracy of the each training algorithm was checked by using test set. As a result, the predicted results which were closest to the experimental results were obtained with the Levenberg–Marquardt training algorithm for bending strength, hardness and density of hybrid composites. These trained values had an average error of 0.376%, 2.969% and 2.648% for bending strength, density and hardness values, respectively.

Interfacial structure evolution and thermal conductivity of Cu-Zr/diamond composites prepared by gas pressure infiltration

Diamond particles reinforced Zr-alloyed Cu matrix (Cu-xZr/diamond, x = 0.25–1.0 wt%) composites were fabricated by gas pressure infiltration. Scanning transmission electron microscopy (STEM) was used to characterize the interfacial structure of the Cu-Zr/diamond composites. The results show that the nucleation of ZrC particles is an inhomogeneous process on both diamond (111) and (100) surfaces, and the ZrC particles prefer to nucleate at (111) facets on both surfaces. The results also show that the interfacial carbide morphology is dramatically influenced by Zr content in the Cu matrix. With increasing Zr content from 0.25 to 1.0 wt%, the interfacial structure evolves from small-sized and discrete ZrC particles to continuous carbide layer. As a result, the thermal conductivity firstly increases and then decreases, and the maximum value is obtained at an intermediate Zr content of 0.5 wt%. This study clarifies the formation mechanism of ZrC at the interface and depicts the interfacial structure evolution in the Cu-Zr/diamond composites. The influence of interfacial structure evolution on composite thermal conductivity is also demonstrated.