Liquid Infiltration Technique Research Articles

Application of Doping Ceramics via Infiltration on Translucent Alumina Ceramics

The feasibility to homogeneously incorporate additives and fabricate translucent alumina ceramics via liquid precursor infiltration technique was substantiated.Pre-sintered alumina compacts with various thickness values were infiltrated with aqueous yttrium nitrate solutions of different concentrations under various conditions.Line-scanning result of yttrium along the sample depth direction was investigated to characterize the doping homogeneity.It is found that better distribution homogeneity and more stringent control of a desired amount of dopants can be realized as the sample thickness and the solution concentration are decreased.By assuming all pores are open and completely saturated,the theoretical model is proposed to predict the amount of incorporated species by infiltration.Finally,translucent alumina ceramics were fabricated.Compared with ball-milling prepared counterparts,samples with improved microstructure and enhanced optical properties are achieved by infiltration.

Microstructure and characteristics of the metal–ceramic composite (MgCa‐HA/TCP) fabricated by liquid metal infiltration

In this article, a novel MgCa alloy-hydroxyapatite-tricalcium phosphate (HA/TCP) composite was fabricated using the liquid alloy infiltration technique. The feasibility of the composite for biomedical applications was studied through mechanical testing, electrochemical testing, immersion testing, and cell culture evaluation. It was shown that the composite had a strength about 200-fold higher than that of the original porous HA/TCP scaffold but retained half of the strength of the bulk MgCa alloy. The corrosion test indicated that the resulting composite exhibited an average corrosion rate of 0.029 mL cm⁻² h⁻¹ in the Hank's solution at 37°C, which was slower than that of the bulk MgCa alloy alone. The indirect cytotoxicity evaluation revealed that 100% concentrated (i.e., undiluted or as-collected) extract of the MgCa-HA/TCP composite showed significant toxicity to L-929 and MG63 cells (p < 0.05). In contrast, the diluted extracts with 50 and 10% concentrations of the MgCa-HA/TCP composite exhibited a similar degree of cell viability (p > 0.05), equivalent to the grade I cytotoxicity of the standard ISO 10993-5: 1999.

Thermal conductivity studies on Si/SiC ceramic composites

Ceramic heat exchangers are increasingly used in many nuclear power plants. Silicon carbide has been treated as a promising material for heat exchanger application since it has good thermal conductivity and corrosion resistance. In this work, four different types of Si/SiC ceramic composites were prepared by liquid silicon infiltration technique. Thermal conductivities of these ceramic composites at different temperatures are measured by the laser flash thermal conductivity method. Results show that the presence of free carbon and voids are notably affecting the thermal conductivity of these materials.

Superconducting Joints Between ${\hbox {MgB}}_{2}$ Wires and Bulks

In many superconducting applications the feasibility of a persistent mode operation is a prerequisite of acceptance of the superconducting solution. Regarding the High Temperature Superconducting oxides, this persistency is obtained only for the bulks and, when realized for large samples as for the BSCCO-2212 material, allows the transport of very limited superconducting currents, with densities of the order of some kA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Instead we were able to maintain in a MgB, ring a persistent current corresponding to several tens of kA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Designing large superconducting systems, based either on wires or on the bulk materials, as the magnets for MRI or for magnetic separation it will be important to realize persistent superconducting joints between the parts, allowing to sustain the high currents needed for these power applications. In the framework of the MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> material development and using the liquid Mg infiltration technique, we have explored the possibility to join wires with bulks and bulks between themselves. The persistency of the joints has been verified by the measurement of the levitation forces of the superconducting system in presence of a permanent magnet and by direct transport current measurements. How to apply the joining technique to the magnet manufacturing is presented.

Effects of Annealing and Nanoparticle Doping on Electrical Properties of ${\rm MgB}_{2}$ Bulks Grown by Reactive Mg Liquid Infiltration Technique

A comparative study of the electron transport properties of MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> bulk samples was performed aimed at addressing the role of annealing as well as of SiC and Zn doping on sample anisotropy and band conduction parameters. Samples were produced by Reactive Mg Liquid Infiltration (RLI) technique in boron powder preforms. Both irreversibility ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">irr</sub> ) and upper critical fields ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c2</sub> ) are enhanced by doping procedure. In all samples the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c2</sub> anisotropy factor (gamma), evaluated by analyzing the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">irr</sub> and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c2</sub> temperature dependence in the framework of the current percolation model proposed by Eisterer <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">et</i> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">al</i> . [Phys. Rev. Lett. 90, 247002 (2003)], decreases at increasing temperature, and it is reduced by SiC and Zn doping-induced defects. Accordingly, in both annealed and doped samples the pi -band diffusivity, obtained by fitting the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c2</sub> dependence on temperature within the two-band model formulated by Gurevich [Phys. Rev. B 67, 184515 (2003)], is higher than the sigma-band one. A decrease of the more anisotropic sigma-band diffusivity was also found in the doped samples.

Effects of Nanoparticle Doping on Electrical Properties of ${\rm MgB}_{2}$ Bulks and Wires Obtained by Reactive Mg Liquid Infiltration Technique

The effect of SiC nanoparticle and colloidal C additions on the electric transport properties of MgB2 samples, bulks and wires, was investigated at different applied magnetic fields. The samples were obtained by the Reactive Mg Liquid Infiltration (RLI) in boron powder preforms, technique with the advantages of good mechanical characteristics of the products with an easy manufacturing. It was found that SiC nanoparticle additions produce an improvement of both the irreversibility field and the upper critical field as well as the enhancement of the n-exponent in the power law voltage-current curves and of the pinning energy. In particular the analysis of the pinning energy dependence on the current density turned out that the SiC doping-induced pinning centers are of similar nature than the pristine ones. Moreover only a slight decrease of the critical temperature was measured as a consequence of the SiC doping. Higher pinning-capability enhancement was found for the C doped wires which exhibit a sharper irreversibility field enhancement at the external field increase. This issue together with a stronger critical temperature decrease (0.7 K) points towards a higher amount of C substitution for B in the MgB2 lattice than in the SiC-doped bulk samples.

Pinning properties in pure and SiC doped MgB2 bulk obtained by reactive Mg liquid infiltration technique

The effects of SiC additions on pinning properties of MgB2 bulk samples, obtained by reactive Mg liquid infiltration (RLI) in Boron powders preforms have been analysed by means of electric transport measurements at different applied magnetic fields. For doped and undoped systems the E vs. J characteristics as well as the pinning energy dependence as a function of the current density has been evaluated and analysed in the framework of thermal creep models. The doping-induced pinning centres, very effective in the pinning property improvements, turned out to be of similar nature than those of the undoped sample and can be mostly attributed to SiC reactive insertions inside the MgB2 grains with an increase of lattice disorder induced by the relative reaction products.

Preparation of Mullite Composite Using Liquid Infiltration Technique

Porous mullite with a porosity of about 78% was fabricated using Al(OH)3, SiO2 and AlF3 powders to develop non-asbestos friction materials for brake pads. A mullite composite was fabricated by infiltrating liquid phenolic resins to the porous mullite. The effects of the processing parameters (infiltration frequency, immersion duration and resin temperature) on the properties of the mullite composite obtained by the liquid infiltration technique were studied. SEM analysis reveals that the parameters affected the degree of infiltration and hardness of the mullite composite by changing the infiltration frequency and immersion duration. With increasing immersion duration and infiltration frequency, the resultant porosity had lower values. In the case of hardness, the measured values showed an opposite tendency.

Microwave response of bulk MgB2 samples of different granularity

The microwave response of three high-density bulk MgB2 samples has been investigated in the linear and nonlinear regimes. The three samples, characterized by different mean size of grains, have been obtained by reactive infiltration of liquid Mg in powdered B preforms. The linear response has been studied by measuring the microwave surface impedance; the nonlinear response by detecting the power radiated by the sample at the second-harmonic frequency of the driving field. Our results suggest that bulk MgB2 prepared by the liquid Mg infiltration technique is particularly promising for manufacturing resonant cavities operating at microwave frequencies.

On the thermal and chemical stability of diamond during processing of Al/diamond composites by liquid metal infiltration (squeeze casting)

Aiming at assessing the feasibility of Al/diamond composites, the present study deals with the thermal stability of different diamond grades under environmental conditions which are characteristic for the selected pressurized liquid melt infiltration technique (squeeze casting). The influence of both the diamond grade, i.e., synthetic and natural, mono- and polycrystalline diamond and the particle size is investigated. The critical parameters with respect to thermal degradation of diamond have been identified. It is shown that as a consequence of their peculiar process history, “micron-grade” diamond powders are particularly susceptible to thermal degradation in the presence of oxygen and that such degradation is most effectively prevented by using hydrogen-containing atmospheres such as forming gas. It is outlined why nanosized diamond powders and polycrystalline diamond powders are not a suitable “reinforcing phase” for Al/diamond composites. Eventually, it is shown that under the conditions prescribed, the liquid metal infiltration technique is principally viable for the processing of sound Al/diamond composites.

The voltage–current relations for MgB2 obtained by reactive liquid infiltration

The reactive liquid infiltration (RLI) technique, applied to-the MgB2 material, has allowed us to obtain either bulk or wire samples of good transport properties. The evaluation of the voltage-current characteristics, V-I-n, for typical samples, measured by transport at temperatures between 4.2 and 30 K, is presented. The behaviour of the n exponent is discussed in terms of a simple model and the differences between bulk and wire samples are outlined. (C) 2003 Elsevier B.V. All rights reserved.

Production of saffil fibre reinforced Zn-Al (ZA 12) based metal matrix composites using infiltration technique and study of their properties

Abstract In this study metal matrix composites of a zinc–aluminium based alloy (ZA-12) and short staple δ-alumina saffil fibres with volume fractions of 0.10, 0.15, 0.20 and 0.30 were produced using a liquid infiltration technique. The densities, hardness, tensile strength and wear properties were examined. The measured densities of the specimens showed that about 90% of the total metal infiltration had taken place at pressures below 1 MPa, and additional pressures up to 3 MPa provided only for the metal infiltration into narrower inter-fibre channels to be completed. The hardness of the composites on both planar and transverse sections increased with the increasing fibre volume fractions, the latter being larger than the former. The tensile strength and the elongation of the composites decreased with increasing fibre volume fractions due to the fibre contact effect. The wear behaviour of the composites was dependent on fibre volume and the applied load. The wear rate of the composites decreased with increasing fibre volume fraction and increased proportionally to the applied load. The wear rate of the unreinforced ZA 12 alloy increased with the load. The coefficient of friction of the composites decreased with increasing applied load and had no definitive trend with the fibre volume fraction. Wear mechanism for the surface of the unreinforced alloy was plastic deformation, whereas for the composites it was the layer deformation on the surface of the composites.

High-pressure, high-temperature sintering of diamond–SiC composites by ball-milled diamond–Si mixtures

A new method of sintering diamond-silicon carbide composites is proposed. This method is an alternate to the liquid silicon infiltration technique and is based on simultaneous ball milling of diamond and silicon powder mixtures. Composites with fine-grain diamonds embedded in a diamond–SiC nanocrystalline matrix were sintered from these mixtures. Scanning electron microscopy, x-ray diffraction, and Raman scattering were used to characterize the ball-milled precursors and the sintered composites. It was found that the presence of diamond micron-size particles in the initial powder mixture promotes milling of silicone particles and their transformation into the amorphous state. Mechanical properties of the composites, sintered from mixtures of different ball-milling history at different pressure–temperature conditions, (6 GPa/1400 °C and 8 GPa/2000 °C) were studied.

Elastic Properties of Short Glass Fiber-Reinforced ZA-27 Alloy Metal Matrix Composites

A well-consolidated composite of ZA-27 alloy reinforced with short glass fiber at volume fractions of 2, 7, 12, and 17% was prepared by liquid infiltration techniques and its elastic properties were determined by destructive testing. The results showed that the modulus of elasticity and ultimate tensile strength of the composite gradually increased with increasing volume fraction of the fiber, although the ductility decreased with an increase in volume fraction of the fibers. In addition, the data obtained from Young’s modulus measurements were compared with theoretical results predicted by the shear-lag model, Nielsen-Chen model, and computational model. The experimental results were shown to be in better agreement with those of the latter two models. The ultimate tensile strength test results were also compared with theoretical results predicted by the shear-lag and Miwa models. The Miwa model agreed favorably with the experimental results.

Dry wear and friction properties of δ-Al 2O 3 short fiber reinforced Al [sbnd]Si (LM 13) alloy metal matrix composites

Planar-randomly oriented alumina short fiber (Saffil) reinforced Al Si (LM 13) alloy metal matrix composites (MMCs) were produced by a modified liquid infiltration technique. The wear and friction behavior of LM 13 alloys containing up to 30 vol % Al 2O 3 fiber were investigated in sliding against a hard steel counterface (63 HRC) by continuous loading experiments carried out in a pin-on-disk machine under dry conditions at room temperature in the transverse section of the composites. Sliding tests were conducted at five loads (5 N, 10 N, 20 N, 40 N and 60 N) and under a constant sliding speed of 1 m/s. The wear and coefficient of friction against sliding distance initially showed a short transient period and then reached a steady state behavior. The wear behavior of the composites was dependent on fiber volume and applied load. The wear rate decreased with increased volume fraction of fiber and increased with increasing load. The wear resistance of the composites over the range of loads and volume fraction of fibers studied was found to range from almost 1.2 to about 4.0 times that of unreinforced alloy. Coefficient of friction decreased with increased fiber volume percent and applied normal load. To analyze wear mechanisms, wear surfaces were examined by scanning electron microscopy and it was found that the wear of the unreinforced alloy and composites occurred by groove formation and its subsequent growth, the magnitude of which increased with increasing fiber volume and applied normal load.

CeO2 as a growth inhibitor of Y2BaCuO5 in a Ba3Cu5Ox liquid phase

Abstract Growth behavior of Y 2 BaCuO 5 (211) second phase particle in a Ba 3 Cu 5 O x liquid phase was investigated by applying the liquid infiltration technique to 211 powder compacts. Heating 211 compacts surrounded by the liquid-forming powders with or without CeO 2 addition to 1100°C and holding for various time periods up to 10 h, the liquid-forming powders melted and infiltrated into 211 compacts. The 211 coarsening in the infiltrated liquid phase with CeO 2 addition was significantly suppressed compared to that in the liquid phase without CeO 2 addition. It is concluded that CeO 2 acts as a grain growth inhibitor for 211.

Low temperature melt process of SmBa2Cu3O7−y using a liquid infiltration technique

Abstract SmBa 2 Cu 3 O 7− y (Sm123) was made by a liquid infiltration technique using isothermal peritectic reaction below the peritectic temperature ( T p =1060°C) of SmBaCuO. By heating and isothermal holding, the coupled Ba 3 Cu 5 O 8 /Sm 2 BaCuO 5 (Sm211) powder compacts in the temperature range of 900°C–1050°C in air, the Ba 3 Cu 5 O 8 powder melts and is then infiltrated into the Sm211 compacted powder. The infiltrated liquid phase reacts with the Sm211 phase to form a textured Sm123 structure. The microstructure and the superconducting properties of the samples are reported.

5531339 Bottle of synthetic resin: Yamanaka Nobu; Fujie Takashi; Hidaka Hirosh; Akiyama Yoshi, Tokyo, Japan assigned to Yoshino Kogyosho Co Ltd

A novel shaping method for the fabrication of reaction bonded silicon carbide structures was investigated in this work. A paste consisting of silicon carbide as inert filler and carbon powder was developed and printed by robocasting technology. Layer by layer deposition of the ceramic paste facilitates the printing of complex shaped structures. Different structures such as lattices, hollow cylinders, bending bars and gyroids were printed using nozzles with diameter of 0.5 mm and 1.5 mm. After pyrolysis at 700 °C and further heat treatment at 1850 °C the samples were infiltrated using the liquid silicon infiltration technique to obtain dense near-net shape RBSC structures. The robocasted structures showed a hardness of approximately 20 GPa, a thermal conductivity of ∼112 W/m*K, Young’s modulus of ∼356 GPa, flexural strength of ∼224 MPa and an amount of residual silicon of approximately 23%. These measured properties are comparable with those of traditionally fabricated RBSC.

Preparation of carbon fibre reinforced aluminium via ultrasonic liquid infiltration technique

Preparation of carbon fibre reinforced aluminium via ultrasonic liquid infiltration technique

Preparation of carbon fibre reinforced aluminium via ultrasonic liquid infiltration technique

AbstractAn ultrasonic liquid infiltration technique has been developed for the fabrication of carbon fibre reinforced aluminium (CF/Al) precursor wires. The principal effect of ultrasound on aluminium infiltration into carbon fibres is considered to be caused by cavitation. The acoustic power required to produce cavitation in the present experimental system has been approximately calculated to be about 150 W, which is much greater than the requirement, several tens of watts, for overcoming the capillary pressure among carbon fibres. The observations on the morphology of the CF/Al precursor wires show that there are generally four states of infiltration: totally non-infiltrated, non-infiltrated in the centre and in some local regions of the wires, and completely infiltrated. It is found that carbon fibres can be sufficiently impregnated by molten aluminium given the appropriate application of ultrasound. Furthermore, a single fibre tensile test shows that there is no strength degradation of carbon fibres a...