Pressureless Infiltration Method Research Articles

Composite castings based on ferrous alloys reinforced by ceramic spatial structure

A method is presented for manufacturing composite castings that are reinforced by ceramic preforms that have a porous spatial structure. The ceramic preforms were made from oxide ceramic in the form of ZrO2 and Al2O3. Composite castings were produced using the pressure-less infiltration method of ceramic preforms with cast steel (CS) and high-chromium cast iron (HCCI). A chemical analysis indicated the positive role of Cr, which promoted a physiochemical interaction between the matrix and the phase reinforcement. The hardness of each of the composite zones was higher by at least 150–350 HV0.1 as compared to the base alloys. The presence of the ceramic phase in the microstructure of the composite zones resulted in improved wear resistance of up to 20%.

Preparation and properties of in situ formed TiCx/high chromium white iron composite with honeycomb structure

The well-formed porous Ti3AlC2 preform with honeycomb structure using mold forming method, and TiCx/high chromium white iron (TiCx/HCWI) composite with fine TiCx framework formed by porous Ti3AlC2 preform in situ decomposition using pressureless infiltration method were successfully prepared, respectively. The HCWI composite with fine in situ TiCx framework exhibited excellent properties. The transition zone between framework and HCWI with the highest hardness, the minimum friction coefficient, wear depth and electronic work function (EWF) may protect the whole sample during wear.

Comparing the Corrosion Resistance of 5083 Al and Al2O33D/5083 Al Composite in a Chloride Environment.

In this study, an Al2O33D/5083 Al composite was fabricated by infiltrating a molten 5083 Al alloy into a three-dimensional alumina reticulated porosity ceramics skeleton preform (Al2O33D) using a pressureless infiltration method. The corrosion resistance of 5083 Al alloy and Al2O33D/5083 Al in NaCl solution were compared via electrochemical impedance spectroscopy (EIS), dynamic polarization potential (PDP), and neutral salt spray (NSS) tests. The microstructure of the two materials were investigated by 3D X-ray microscope and scanning electron microscopy aiming at understanding the corrosion mechanisms. Results show that an Al2O33D/5083 Al composite consists of interpenetrating structure of 3D-continuous matrices of continuous networks 5083 Al alloy and Al2O33D phase. A large area of strong interfaces of 5083 Al and Al2O33D exist in the Al2O33D/5083 Al composite. The corrosion development process can be divided into the initial period, the development period, and the stability period. Al2O33D used as reinforcement in Al2O33D/5083 Al composite improves the corrosion resistance of Al2O33D/5083 Al composite via electrochemistry tests. Thus, the corrosion resistance of Al2O33D/5083 Al is higher than that of 5083 Al alloy. The NSS test results indicate that the corrosion resistance of Al2O33D/5083 Al was lower than that of 5083 Al alloy during the initial period, higher than that of 5083 Al alloy during the development period, and there was no obvious difference in corrosion resistance during the stability period. It is considered that the elements in 5083 Al alloy infiltrated into the Al2O33D/5083 Al composite are segregated, and the uniform distribution of the segregated elements leads to galvanic corrosion during the corrosion initial period. The perfect combination of interfaces of Al2O33D and the 5083 Al alloy matrix promotes excellent corrosion resistance during the stability period.

Fabrication, mechanical properties, and wear behaviors of co-continuous TiC-steel composites

In this study, the co-continuous TiC-steel composites with the same volume content of 90% but different 3D networks of TiC ceramics reinforcement, namely CP1 (network of pure TiC), CP2 (network of TiC mixed with Ti) and CP3 (network of TiC coated by Ti), were fabricated by using the pressureless infiltration method. The microstructure, mechanical properties, and wear properties of the co-continuous composites against a Si3N4 ball were tested comparing to a brake disc material. The results show that the ceramics network reinforcement of the composites CP1, CP2 and CP3 possessed partially continuous, weakly continuous and strongly continuous structure respectively, and the CP3 showed superior mechanical properties. The three co-continuous composites CP1, CP2 and CP3 possessed similar friction coefficients to the brake disc material, but 59.9%, 76.1% and 81.6% lower specific wear rates than that of the brake disc material, respectively. The wear mechanisms of the co-continuous composites were preliminarily explored.

Impact of Ce2O3 on microstructure and properties of matrix-body for PDC drill bits synthesized via pressureless melt infiltration

The materials of matrix-body polycrystalline diamond composite (PDC) bits were fabricated through pressureless melt infiltration method at 1200 °C for 1 h within vacuum furnace using molten CuNi metallic binder, Ni and WC powders (including cast WC, spherical WC, and fine WC). Various weight ratios of Ce2O3/(WC + Ni + CuNi) ranging from 0 to 0.01 were added to matrix-body materials. The influence of Ce2O3 on the microstructure, phase formation, phase transformations, and related mechanical properties of matrix-body materials was thoroughly investigated. The results show that experimental temperature led to the decomposition of WC and partial dissolution of W and C in CuNi binder alloys. In matrix-body materials with no Ce2O3 addition, only new W2C phase was formed. With further increase in Ce2O3/(WC + Ni + CuNi) ratios, spherical WC was dispersed into smaller WC particles. Meanwhile, new phases (namely Ni2W4C, C, and W2C) were found. The material exhibited an optimal hardness (HRA = 93.7) and transverse rupture strength (1846.8 MPa) when Ce2O3/(WC + Ni + CuNi) ratio was 0.006. However, impact toughness was slightly decreased, while the highest value of 6.45 J cm−2 was measured for the sample with Ce2O3/(WC + Ni + CuNi) ratio of 0.01.

Enhanced hardness and toughness in WC/W2C-Ni-Cu composites fabricated by selective laser melting

Dual-grain WC/W2C-Cu-Ni composites were fabricated by selective laser melting using a mixture of Ni-coated WC-W2C and CuNi powders. The phase composition and microstructure of the processed composites were investigated by X-ray diffraction, scanning electron microscopy, electron backscattered diffraction and transmission electron microscopy techniques. The results revealed that the microstructure of composites was consisting of both partially melted WC-W2C particles and nano-WC grains evenly distributed in the CuNi binder phase. The existence of WC1-x phase was detected between nano-WC and CuNi phases. An interface formed between protruding parts, existing around the partially melted WC-W2C particle, and CuNi resulted in the increase of the contact area and bonding strength between the partially melted WC-W2C particles and the matrix. The mechanical properties (hardness, bending strength and toughness) of the composites processed in this research were investigated and compared to those of parts fabricated by pressureless infiltration. The dual-grain structure of the composites enhanced their mechanical properties compared to those of traditional WC composites processed by a pressureless infiltration method.

Highly conductive graphite matrix/copper composites by a pressureless infiltration method

Graphite matrix/copper composites have found significant potential uses in numerous areas. Until now, a high ambient gas pressure has to be applied to overcome the non-wettability between the copper melt and graphite matrix, which has restricted the technological and economic efficiencies, as well as the composite performance. In this paper, we have proposed a pressureless infiltration strategy to realize the preparation of highly conductive graphite matrix/copper composites. A tungsten carbide network is first in situ constructed in the graphite matrix, transforming the capillary force from the resistance mode to the impetus mode. Results show that the contact angle of graphite/copper decreased from 138.5° to 23° due to the constructed tungsten carbide network. The composites exhibit good interfacial bonding, and the electrical conductivity reaches 15.1 × 105 S/m, far higher than the requirement of the industry standard.

Effect of tungsten based coating characteristics on microstructure and thermal conductivity of diamond/Cu composites prepared by pressueless infiltration

Tungsten coatings were deposited on diamond particles by vacuum magnetron sputtering. The coated diamond particles were firstly heat treated at different temperatures, and diamond/copper (Cu) composites were fabricated by using a pressureless infiltration method afterwards. The influences of heat treatment on the microstructure and composition of tungsten based coating surface and diamond/copper composites were analysed. Notable differences were found in the microstructure with heating temperatures. Moreover, the tungsten based coating surface contained large quantities of oxidised tungsten, and the phase composition of the coatings varied within the range of tungsten–W2C–WC as the heat treatment temperature increased. The fracture surface morphologies in the copper matrix composites reinforced with diamond particles with coatings were identically characterised with the presence of ductile fracture of matrix accompanied by dissociation of diamond particles from the matrix. The thermal conductivity (TC) and gas tightness behaviours of the diamond/copper composites were also explored. A maximum TC of 768 W m−1 K−1 and a fine gas tightness of 2.5 × 10-10 Pa m3/s were obtained with reinforcement of tungsten-coated diamond particles treated at 800 °C. The value of the interface thermal resistance between copper and diamond particles was also estimated and specifically discussed.

Research and numerical simulation of thermal conductivity of SiCp/6061Al composite fabricated by pressureless infiltration

In this paper, finite element models of SiCp/6061Al composites with different volume fractions of SiC particles with W50/W14 and W85/W28 ratios of 2:1 were constructed using digimat software. Then the model was introduced into ABAQUS finite element software for thermal conduction simulation. The thermal conductivity of SiCp/6061Al composites was calculated and the effects of different volume fractions and particle sizes on the thermal conductivity of the composites was obtained. Then The thermal conductivity results of the finite element simulation are compared with theoretical model values and the experimental values of SiCp/6061Al composites prepared by pressureless infiltration method. it is found that the thermal conductivity changes of the three results are consistent, and the thermal conductivity of SiCp/6061Al composites increases with the volume fraction and size of SiC particles, the experimental values are small due to the experimental deviation and the existence of defects.

Fabrication, microstructure and mechanical properties of co-continuous TiCx/Cu-Cu4Ti composites prepared by pressureless-infiltration method

The co-continuous TiCx/Cu-Cu4Ti composites were prepared by infiltrating melting Cu into TiC0.5 porous preforms. TiC0.5 porous preforms were firstly synthesized by in-situ solid reaction process using powder Ti and carbon black as the starting materials, PVB as shaping and pore-forming agent. The prepared TiC0.5 preforms showed 3D-connected visible pores characterized with two classes of sizes, i.e. intergranular pores with size of 10–30 µm and intracrystalline pores with 2–3 µm. Microstructure and phase compositions of the composites were detected by scanning electron microscopy (SEM) equipped with EDS and X-ray diffraction (XRD). Metal region of the composites contained Cu as well as a new phase Cu4Ti, which was formed by reaction of Cu and TiC0.5. Composites prepared by this method had a compact structure and strong interface. Meanwhile, metal phase and ceramic phase maintained a co-continuous structure in three dimensions. Cu-Cu4Ti entered into the TiCx ceramic particles like root structure during the infiltration process. Flexural strength, fracture toughness and Vickers hardness of the composites reached 948.20 ± 124.04 MPa, 12.62 ± 0.37 MN m−3/2 and 606.4 ± 36.7 respectively when content of TiCx was 71.22 vol%.

Interface design in 3D-SiC/Al-Si-Mg interpenetrating composite fabricated by pressureless infiltration

3D-SiC/Al-Si-Mg interpenetrating composites (IPCs) were fabricated by pressureless infiltration method. Interfaces in the 3D-SiC/Al-Si-Mg IPCs were modificated by using two different kinds of aluminum alloy Al-15Si-10Mg and Al-9Si-6Mg to infiltrate into 3D-SiC performs and different treated 3D-SiC preforms unoxidized or preoxidized in air at 1000 °C, 1100 °C and 1200 °C for 2 h respectively. Results showed that desired interfaces can be achieved in both IPCs made with those two aluminum alloys, as demonstrated by their excellent comprehensive properties. When the Al-15Si-10Mg alloy with excessive Si content is used for infiltration, interfaces in 3D-SiC/Al-Si-Mg IPC fabricated with the unoxidized 3D-SiC preform are directly bonded through atomic matching without any interfacial reaction and the composite has the properties of a thermal conductivity (TC) of 224.5 W/(m °C), a thermal expansion coefficient (CTE) (RT ~ 300 °C) of 7.04 × 10−6/°C and a bending strength (BS) of 277 MPa. When the Al-9Si-6Mg alloy with a lower Si content is used for infiltration, interface zone with a thickness around 200 nm forms in the 3D-SiC/Al-Si-Mg IPC fabricated with the 3D-SiC preform preoxidized at 1000 °C. The reaction-bonded interface is composed of AlN and MgAl2O4 which have better interface affinity with SiC and can isolate SiC effectively from liquid Al against the formation of detrimental Al4C3 phase. The composite has the properties of a TC of 219.5 W/(m °C), a CTE (RT ~ 300 °C) of 7.66 × 10−6/°C and a BS of 318 MPa.

Fabrication and performance of micro-diamond modified C/SiC composites via precursor impregnation and pyrolysis process

Micro-diamond modified C/SiC (C/SiC-D) composites were fabricated using pressureless infiltration (PI) and precursor impregnation and pyrolysis (PIP) methods. The influence of micro-diamond addition on the ablation and mechanical properties of C/SiC composites was discussed. Results show that, compared with C/SiC composites, the thermal conductivity of C/SiC-D composites improves 33.7% due to the good thermal properties of diamond particles and the strong connection with SiC matrix. Meanwhile, C/SiC-D composites exhibit significantly enhanced ablation resistance, with the linear ablation rate decreasing by 43.3%, from 0.030 mm s−1 to 0.017 mm s−1. The introduction of micro-diamond only brings a limited enhancement to the mechanical properties of C/SiC composites due to the small size and low content of the diamond caused by the limitation of PI method.

Al alloy/Ti3SiC2 composites fabricated by pressureless infiltration with melt-spun Al alloy ribbons

Al alloy/Ti3SiC2 composites with compressive strengths ranging from 743 to 932MPa have been successfully fabricated by a new two-step pressureless infiltration method. 6061 Al alloy ribbons prepared by melt spinning were employed as the Al alloy matrix for melt infiltration. Shifts in phase constitution and reaction mechanisms of Ti3SiC2 preforms in molten Al at 950°C were investigated, and the compression performance of Al alloy/Ti3SiC2 composites was tested. The Vickers hardness of the composites was enhanced to a maximum of 751 HV by increasing the Al content.

Preparation and anisotropic compressive deformation behaviors of tungsten fiber reinforced Cu-Zn matrix composite

For the purpose of fabricating materials with a good “self-sharpening” capacity, the tungsten fiber reinforced Cu-Zn matrix composite was successfully fabricated by the pressureless infiltration method, and the microstructure of the prepared composite was investigated. To investigate the anisotropic mechanical properties, the quasi-static and the dynamic compressive deformation behaviors of the composite in different loading directions were investigated. The angles between the loading direction and the tungsten fiber orientation are 0°, 45° and 90°, respectively. The failure mechanisms of the composite loaded in different directions were investigated systematically. Finally, the “self-sharpening” capacity of the composite was investigated by a ballistic impact experiment, and the mechanism of the “self-sharpening” capacity was discussed.

Enhanced thermal conductive 3D-SiC/Al-Si-Mg interpenetrating composites fabricated by pressureless infiltration

A high thermal conductive 3D-SiC/Al-Si-Mg interpenetrating composite (IPC) with three dimensional mutually interpenetrated structure was fabricated by mold-forming and pressureless infiltration method. Al-15Si-10Mg was used as the infiltration aluminum alloy. The obtained composite was treated with a T6 procedure. The composed phases, microstructure, thermal conductivity, mechanical strength and fractography of the prepared 3D-SiC/Al-Si-Mg IPC were either analyzed or measured with X-ray diffraction (XRD), optical metallography, laser thermal conductivity instrument, universal testing machine, field emission electron scanning microscopy (SEM) with energy dispersive spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM), and etc. The results showed that both SiC ceramic and aluminum alloy phases distribute evenly and form a three-dimensional mutually interpenetrated structure in the obtained IPC. No clear brittle and harmful Al4C3 phase was found in the composite. The obtained IPC contains a SiC volume fraction of 67vol% and has the properties of a density of 3.02g/cm2, a thermal conductivity of 233.6W/(m°C), a thermal expansion coefficient (RT~300°C) of 7.03×10−6/°C and a bending strength of 288MPa.

Diamond/Cu Composites Fabricated by Pressureless Infiltration Method

Copper matrix composites reinforced diamond (diamond/Cu) composites were successfully fabricated by pressureless infiltration method. The composition and structure of the coating are investigated using scanning electron microscopy(SEM), X-ray diffraction. The results indicate that the composition of the coatings is WC which is uniform on diamond. The microstructure and properties of diamond/Cu composites were investigated. The results show that the diamond/Cu composites were compact and WC transition layers onto diamond can greatly promote the compatibility between diamond and Cu. Further investigation reveals that the diamond/Cu composites possess low density (5.3907g/cm³), excellent thermal management function as a result of high thermal conductivity up to 761.1 W/(m•K) and a fine tightness (2.5×10^-10 Pa•m³/s).

Investigation on the penetration performance and “self-sharpening” behavior of the 80W–14Cu–6Zn penetrators

In order to investigate the penetration performance of the 80W–14Cu–6Zn alloy prepared by the pressureless infiltration method, ballistic impact experiments were conducted, and the 90W–7Ni–3Fe alloy and 35CrMnSiA alloy were tested for comparison. The 80W–14Cu–6Zn penetrator exhibits the best penetration performance with the penetration depth of 30.35mm which increases by 29.9% and 99.0% respectively compared with the penetrators made of 90W–7Ni–3Fe alloy and 35CrMnSiA alloy. The remnant of the 80W–14Cu–6Zn penetrator maintains an acute head indicating an excellent “self-sharpening” capacity. On contrast, both the remnants of the 90W–7Ni–3Fe and 35CrMnSiA penetrators show mushroom-like heads. Microstructure analysis indicates that high strength and proper critical failure strain are responsible for the “self-sharpening” effect of the 80W–14Cu–6Zn penetrator. While the 80W–14Cu–6Zn alloy penetrator is subjected to ballistic impact, plastic deformation occurs to the head of the penetrator mainly and deformation layer is formed on the surface of the penetrator. When the plastic strain of the deformed layer reaches the limit of the critical failure strain, the deformed parts will fall off in timely fashion leading to the formation of the acute head. Besides, due to severe impact between the penetrator and the target plates, Cu–Zn matrix has been squeezed out and formed thin Cu–Zn alloy film coating on the wall of the shot hole, which can act as the lubricant and reduce the friction between the penetrator and the target plates. Both the “self-sharpening” capacity and “self-lubricating” effect of the 80W–14Cu–6Zn alloy eventually optimize the penetration performance.

Effects of heat treatment on phase contents and mechanical properties of infiltrated B4C/2024Al composites

The B4C/2024Al composites were successfully produced by pressureless infiltration method, and the effects of heat treatment on phase content and mechanical properties were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and mechanical properties testing. The results show that phases of B4C/2024Al composites include B4C, Al, Al3BC, AlB2 and Al2Cu. The phase species remain unchanged; however, the phase content of the composites changes significantly after heat treatment at the temperature of 660, 700, 800 or 900 °C for 12, 24 or 36 h. It is found that the heat treatment results in not only considerable enhancement in hardness, but also reduction in bending strength of the composites. Heat treatment at 800 °C for 36 h does best to hardness of the composites, while at 700 °C for 36 h it is the most beneficial to their comprehensive mechanical properties.

Study on improving “self-sharpening” capacity of W–Cu–Zn alloy by the pressureless infiltration method

In order to improve the “self-sharpening” capacity of the tungsten heavy alloy (WHA) for kinetic energy projectile application, the WHAs should have not only high strength but also proper critical shear failure strain. For the purpose of fabricating the WHAs with high strength and proper critical shear failure strain, in the present study, the WHA composed of 80W–14Cu–6Zn was prepared by W skeleton infiltrated of Cu–Zn alloy. The microstructure and mechanical properties were systematically investigated. Microstructure analysis shows that W particles are connected to form W skeleton, and the interstice of W skeleton is filled up with α phase Cu–Zn alloy which has lamellar feature resulting from spinodal decomposition during the preparation process. Due to the solid solution strengthening effect of Zn in the matrix, the static yield strength and the dynamic yield strength of the 80W–14Cu–6Zn alloy are respectively enhanced by 200MPa and 400MPa compared with those of the 80W-20Cu alloy. Moreover, due to the proper ductility of the Cu-Zn alloy matrix, under the uniaxial dynamic compression test, the critical shear failure strain of the 80W–14Cu–6Zn alloy is effectively controlled within 0.2–0.4, which is beneficial to promote “self-sharpening” effect during the penetration process for kinetic energy projectile application. Additionally, the failure mechanism of the 80W–14Cu–6Zn alloy under dynamic compression was discussed. The ballistic impact experiment has proved that the 80W–14Cu–6Zn alloy exhibits remarkable “self-sharpening” capacity.

Computational and Experimental Investigation on Thermal Conductivity of SiС Particle Reinforced Al-Matrix Composite Containing Pores

In this paper, the finite element method (FEM) was implemented to determine the effective thermal conductivity of SiC particle reinforced Al matrix (SiCp/Al) composites containing various pores and that method was validated by experimentation. A commercially available finite-element package ANSYS is used to for this numerical analysis. Multi-particle and pores random distribution models based on the effective medium approximation (EMA) scheme are constructed to simulate the microstructure of composite materials for various porosities ranging from 0.96 to 10.58%. The SiCp/Al composites were fabricated by the pressureless infiltration method. This study shows that the smaller pores contained in the composite results in sharp reduction of thermal conductivity, when the porosity is up to 2.66 vol.%, the thermal conductivity of composite is found to decrease by about 9.02%. The experimentally measured thermal conductivity values are compared with the numerically calculated ones and also with the existing theoretical and empirical models. The values obtained from finite-element analysis (FEA) are found to be in reasonable agreement with the experimental values.