• Journal of the Korean Ceramic Society
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• v.40 no.10
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• pp.998-1004
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• 2003

With starting materials of two different powder mixtures, $Al_2$(S $O_4$)$_3$+xNa$_2$B$_4$ $O_{7}$$.$10$H_2O$(㏖ ratio; x=0.1, 0.7) and ${\gamma}$-Al$_2$ $O_3$+xNa$_2$B$_4$ $O_{7}$$.$10$H_2O$(㏖ ratio; x=0.1, 0.7), whisker-type $Al_{18}$B$_4$ $O_{33}$ particles were synthesized by using conventional and microwave heat-treatment. The effects of microwave, amount of flux and temperature on the growth of whisker-type $Al_{18}$B$_4$ $O_{33}$ particles were investigated by using X-Ray Diffractometry (XRD) and Scanning Electron Microscopy (SEM). With increase of heat-treatment temperature and amount of flux, the size of whisker-type $Al_{18}$B$_4$ $O_{33}$ particles increased in both conventional and microwave heat-treated samples. However, compared to the conventional heat-treated samples, whisker-type $Al_{18}$B$_4$ $O_{33}$ particles were well grown for the microwave heat-treated samples.ted samples.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.154.1-154
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• 2003

• Korean Journal of Metals and Materials
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• v.49 no.3
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• pp.270-274
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• 2011

Plasma electrolytic oxidation (PEO) treatment was performed on squeeze cast AZ31 alloy and $Al_{18}B_4O_{33}w/AZ31$ composite. Scanning electron microscope (SEM) was employed to characterize the surface morphology and cross-section microstructure of the coating. The phase structures of the PEO coating were analyzed by X-ray diffraction (XRD). The corrosion resistance of the PEO coating was evaluated by electrochemical method. The results showed that the $Al_{18}B_4O_{33}$ whisker on the surface of the composite was decomposed and $MgAl_2O_4$ was formed in the PEO coating layer of $Al_{18}B_4O_{33}w/AZ31$ composite during PEO treatment. As a result, the electrochemical corrosion potential of the PEO coated $Al_{18}B_4O_{33}w/AZ31$ composite was increased compared with that of AZ31 alloy.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.10
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• pp.1583-1589
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• 2001

Metal matrix composites with whisker reinforcements have significant potentials for demanding mechanical applications including defense, aerospace, and automotive industries. Especially metal matrix composites, which are reinforced with aluminum borate whisker, have been used leer the part of piston head in automobile because of good specific strength and wear resistance. In this study, AC4CH-based metal matrix composites with $Al_{18}$B$_{4}$ $O_{33}$ reinforcement have been produced using squeeze casting method, after T6 heat treatment, we evaluated fatigue life property of matrix and MMC composite and investigated fracture mechanism.m.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.335-340
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• 2002

In recent years, the study of metal matrix composite has increased specially, aluminum alloy, research and development are briskly progress to find new metal matrix composite. this study is following the this purpose; This study is used metal matrix composite that was produced by matrix, AC4CH. and reinforcement $A_{18}B_4O_{33}$ metal matrix composite to add $Al_2O_3,\;TiO_2$ for strengthen of binding together among the Whisker. Each Metal matrix composite is produced using the squeeze casting method. Fracture tounghness test was in accordance with the provisions of ASTM E399; Specimen was produced half-size CT specimen W=25mm, B=12.5mm, Cross head speed 0.05mm/min in room temperature. The plane strain fracture toughness $K_{IC}$ is $8.7MPa-m^{0.5}$ for $Al_{18}B_4O_{33}$/AC4CH., $9.28MPa-m^{0.5}$ for $Al_{18}B_4O_{33}$/AC4CH added $TiO_2$. and $Al_2O_3$ but AC4CH alloy was violated the critical stipulated by ASTM standard for a valid measurement of $K_{IC}$. In case of, it was performed $I_{IC}$ test instead of $K_{IC}$ based on ASTM E 1820

• Korean Journal of Metals and Materials
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• v.48 no.10
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• pp.957-963
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• 2010

The aging behavior of aluminum borate whisker ($Al_{18}B_4O_{33}$) reinforced AS52+Sr magnesium matrix composites was investigated with Vickers hardness measurements, bending tests, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Experimental results showed that aging is accelerated in the $AS52+Sr/Al_{18}B_4O_{33}$ composite compared with an unreinforced AS52+Sr alloy. The hardness of the alloy and composite increases monotonically as a function of the aging time before reaching its peak hardness and then gradually decreases. The composite reaches its peak hardness in 10 h, whereas the matrix alloy requires 30h, indicating accelerated age-hardening in the $AS52+Sr/Al_{18}B_4O_{33}$ composite compared with the unreinforced AS52+Sr alloy at $170^{\circ}C$. The interfacial reaction of $AS52+Sr/Al_{18}B_4O_{33}$ magnesium matrix composite is considered to play a dominant role in the strengthening mechanism, ultimately affecting the mechanical properties of the composite.

• Korean Journal of Metals and Materials
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• v.48 no.5
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• pp.469-475
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• 2010

In this study, the interfacial bond strength of a squeeze infiltrated $Al_{18}B_{4}O_{33}$/AS52 Mg composite was investigated by using a finite element method. Three types of Mg composites with volume fractions of 15, 25 and 35% were fabricated. Three-dimensional models of the composite were developed by using a unit cell model in order to determine the effective elastic modulus of the metal matrix composite and the interfacial bond strength between the whisker and magnesium matrix. After modeling, numerical results were compared with the experimental tensile test results of $Al_{18}B_{4}O_{33}$/AS52 Mg composites. The results showed that the effective modulus of the composite strongly depended on the interfacial strength between the matrix and reinforcement. Based on the numerical and experimental findings, it was found that the strong interfacial bond was achieved by the interfacial reaction product of 30 nm thick MgO, which led to an improvement in the mechanical properties of the $Al_{18}B_{4}O_{33}$/AS52 Mg composites.

• Journal of Korea Foundry Society
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• v.28 no.6
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• pp.268-272
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• 2008

Interfacial characteristics of aluminum borate whisker reinforced AS52 matrix composite was investigated. Peak hardness of AS52 composite was obtained aging at $170^{\circ}C$ for 15h and the aging process was accelerated by the presence of the aluminium borate whisker. The MgO layer, which was the interfacial reaction product between the reinforcement and the Mg matrix, was produced with 20 nm thickness in as-cast condition. As the aging time increased, the thickness of the interfacial reaction layer increased to 50 nm in peak aged condition. The nano-indentation test results indicated that the strength of interface was improved by the aging but over-aging degraded the reinforcement and decreased the interfacial strength which resulted in the decrease of overall composite strength.

• Journal of Powder Materials
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• v.5 no.3
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• pp.199-209
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• 1998

A new low melting inorganic binder, monoclinic $HBO_2$, has been developed for Selective Laser Sintering (SLS) of alumina powder by dehydration process of boron oxide powder in a vacuum oven at $120^{\circ}C$. It led to better green SLS parts and higher bend strength far green and fired parts compared to other inorganic binders such as aluminum and ammmonium phosphate. This appeared to be due to its low viscosity and better wettability of the alumina particle surface. A low density single phase ceramic, aluminum borate ($Al_{18}B_4O_{33}$), and multiphase ceramic composites, $A_{12}O_3-A_{14}B_2O_9$, were successfully developed by laser processing of alumina-monoclinic $HBO_2$ powder blends followed by post-thermal processing; both $Al_{18}B_4O_{33}$ and $A_{14}B_2O_9$ have whisker-like grains. The physical and mechanical properties of these SLS-processed ceramic parts were correlated to the materials and processing parameters. Further densification of the $A_{12}O_3-A_{14}B_2O_9$ ceramic composites was carried out by infiltration of colloidal silica, and chromic acid into these porous SLS parts followed by heat-treatment at high temperature ($1600^{\circ}C$). The densities obtained after infiltration and subsequent firing were between 75 and 80% of the theoretical densities. The bend strengths are between 15 and 33 MPa.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.61-66
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• 2003

In this paper, the effect of binder additive on the fracture toughness was metal matrix composite produced by squeeze casting method. In this study using the matrix is AC4CH and reinforcement used Aluminum borate whisker. Each MMC was produced by add inanimate binder ($SiO_2,\;Al2O_3,\;TiO_2$) to whiskers for increase the binding together of whiskers. Fracture toughness test were carry out in accordance with the ASTM E-399 standard test method, W=25mm, b=12.5mm CT(half size) specimen. However Base metal AC4CH was not meet the qualification of $P_m/P_Q<1.1$, so that test were performed $J_{IC}$ test. $K_{J_{IC}}$ value was measuring by $J_{IC}$ value change into $K_{IC}$. $J_{IC}$ test was carry out in accordance with the ASTM 1820.