표면 개질에 의한 상압에서의 B₄C/Al복합체 제조 방법

임경란,강덕일,김창삼 한국세라믹학회 2003 한국세라믹학회지 Vol.40 No.2

B$_4$C 분말 표면을 알루미나 전구체로 표면 개질하여 알루미늄의 wetting 각을 낮추어 알루미늄의 함침을 용이하게 함으로써 상압에서 B$_4$C/Al 복합체를 제조하고자하였다. 알루미나 전구체에 의한 표면개질은 제타전위의 변화로 확인하였으며, 표면개질된 B$_4$C 분말의 preform에 Al 6061 디스크를 올려놓고 흐르는 알곤 분위기에서 103$0^{\circ}C$/20분 열처리로 Al이 완전히 함침된 B$_4$C/Al 복합체를 제조하였다. 반면 표면 개질되지 않은 B$_4$C 분말은 125$0^{\circ}C$/30분에도 함침이 일어나지 않았다. 이 복합체의 XRD와 SEM 분석은 B$_4$C. Al 외에도 반응상 $Al_3$BC 상이 생성되었으며, 물성을 크게 저하시키는 A1$_4$C$_3$는 생기지 않았음을 보여 주었다. Formation of$B_4C/Al$composite by pressureless infiltration was investigated by lowering wetting angle via surface modification of $B_4C$powder with alumina precursor. Surface modification was confirmed by zeta potential analysis. The$B_4C/Al$composite was prepared by placing an Al 6061 disk on the$B_4C$preform and heating at $1030{\circ}C$/20 min under a flowing argon, but no infiltration took place for a bare $B_4C$ preform even at$1250{\circ}C$/30 min. Analysis of XRD and SEM showed the $Al_3BC$phase besides$B_4C$and Al, but no trace of deteriorative$A1_4C_3$.

TiB₂코팅이 함침법으로 제조되는 B₄C/Al 복합체의 기계적 특성에 미치는 영향

김선혜,임경란,심광보,김창삼 한국세라믹학회 2003 한국세라믹학회지 Vol.40 No.8

B$_4$C/Al 복합체의 기계적 물성은 제조 과정에서 B$_4$C와 Al의 반응에 의한 반응생성물의 종류와 양에 의해서 결정되므로, 강하고 경량 소재로서의 특성이 요구되는 복합체를 만들려면 반응생성물을 조절할 필요가 있다. TiB$_2$는 알루미늄과 반응성이 거의 없고 B$_4$C보다 낮은 접촉각(100$0^{\circ}C$에서 85$^{\circ}$)을 가지고 있다. 그러므로 B$_4$C를 TiB$_2$로 코팅하면 B$_4$C/Al복합체를 함침법으로 제조하는 경우 알루미늄의 함침 온도를 낮출 수 있다. 본 연구에서는 TiB$_2$가 B$_4$C/Al 복합체의 미세구조와 기계적 특성에 미치는 영향을 조사하였다. TiB$_2$를 코팅한 B$_4$C 분말을 졸겔법을 이용하여 준비하였다. B$_4$C 입자에 코팅된 TiB$_2$ 입자 크기는 20-50 nm이었다. TiB$_2$를 코팅하고 제작한 B$_4$C/Al 복합체에는 l7wt%의 미반응 알루미늄이 남아있었고, 코팅하지 않고 제작한 것에는 l4 wt%가 남았다. 결과적으로 코팅하고 제작한 복합체는 코팅하지 않고 제작한 것보다 파괴인성은 높고 경도는 낮았으며, 이러한 결과에서 TiB$_2$가 알루미늄의 함침 온도를 낮추고 B$_4$C와 Al이 반응하는 것을 억제하고 있다는 것을 알 수 있었다. The mechanical properties of B$_4$C/Al composites normally depend on the species and quantity of reaction products between B$_4$C and Al and then the control of reaction products is necessary to make desirable composites for lightweight advanced or armor materials. TiB$_2$ is chemically inert with aluminum and has a lower contact angle (85$^{\circ}$ at 100$0^{\circ}C$) to liquid aluminum than B$_4$C. Thus, TiB$_2$ coating on B$_4$C may lower infiltration temperature of aluminum when the B$_4$C/Al composites is fabricated by infiltration process. In this study, the effects of TiB$_2$ on the microstructure and mechanical properties of the B$_4$C/Al composites have been investigated. TiB$_2$ coated B$_4$C powder was prepared using the sol-gel technique. It was found that the B$_4$C surface is homogeneously covered with TiB$_2$ having a particles size of 20-50 nm. While the B$_4$C/Al composites prepared by infiltration after TiB$_2$ coating had 17 wt% of unreacted Al, on the other hand, the B$_4$C/Al composites without coating included 14 wt% of Al. As a result, the composites infiltrated after the coating showed higher fracture toughness and lower hardness. This strongly suggests that TiB$_2$ not only lowers the infiltration temperature, but also inhibits the reaction between B$_4$C and Al.

고압 자전 고온반응 합성법에 의한 B₄C-Al₂O₃복합분말 제조

임경란,강덕일,김창삼 한국세라믹학회 2003 한국세라믹학회지 Vol.40 No.1

Composite powder of$B_4C-A1_2O_3$was prepared from a mixed powder of$B_2O_3/A1/C$by SHS under argon pressure instead of using a chemical furnace. A mixture of$B_2O_3,$Al and C powder (equivalent amounts to the reaction,$2B_2O_3+4A1+C=B_4C+2A1_2O_3)$was ball milled for 2 h. The mixed powder was placed in a SHS reactor and filled with 10 atm of argon gas and ignited. The inner and outer products were the same by XRD analysis. It was consisted of a composite powder of$B_4C-A1_2O_3$without $AlB_{12}/C_2$which was always produced using a chemical furnace. The composite powder was about$60~100{mu}m$size which was composed of crystalline particles of about 0.3~l${mu}m$size. But when 15 atm of argon was employed, partial sintering took place to give rise hard composite powder of$15~25{mu}m$$B_4C$with $0.1~0.2{mu}m$$A1_2O_3.$ 정량의 B$_2$O$_3$/A1/C의 혼합분말을 화학노 대신 고압의 알곤 분위기를 사용하여 SHS 공정으로 B$_4$C-A1$_2$O$_3$ 복합분말을 제조하였다. 2B$_2$O$_3$+4A1+C=B$_4$C-2A1$_2$O$_3$의 반응식에 해당하는 B$_2$O$_3$(-100 메쉬), Al(-200 메쉬), C(-200 메쉬)의 분말을 2시간 건식 볼밀로 혼합한 후, 고온 고압의 SHS 반응기에 넣고 약 10기압의 알곤 분위기에서 점화하여 SHS을 일으켰다. 반응 생성물은 XRD 분석으로 안과 겉이 균일하게 반응이 일어났으며 반응 생성물로 화학노 사용시 동반되는 부산물 AlB$_{12}$C$_2$가 없는 B$_4$C-A1$_2$O$_3$ 복합 분말을 얻었다. 이 복합 분말은 SEM으로 보면 약 0.3~l $mu extrm{m}$ 크기의 결정이 모인 약 60~100$\mu\textrm{m}$ 크기이었다. 그러나 약 15기압을 사용하였을 때는 부분 소결이 일어나 15~25$\mu\textrm{m}$ B$_4$C 분말에 0.1~0.2$\mu\textrm{m}$의 알루미나가 분산되어 있는 고강도의 복합 분말이 생성되었다.

B₄C 함량에 따른 6061 Al-B₄C 복합분말의 소결 특성 연구

박진주,홍성모,김경열,이민구,이창규,이원혁,이양규,Park, Jin-Ju,Hong, Sung-Mo,Kim, Kyoung-Yeol,Lee, Min-Ku,Rhee, Chang-Kyu,Rhee, Won-Hyuk,Lee, Yang Kyu 한국분말야금학회 2013 한국분말재료학회지 (KPMI) Vol.20 No.3

In the present work, 6061 Al-$B_4C$ sintered composites containing different $B_4C$ contents were fabricated and their characteristic were investigated as a function of sintering temperature. For this, composite powders and their compacts with $B_4C$ various contents from 0 to 40 wt.% were fabricated using a planetary ball milling equipment and cold isostatic pressing, respectively, and then they were sintered in the temperature ranges of 580 to $660^{\circ}C$. Above sintering temperature of $640^{\circ}C$, real density was decreased due to the occurrence of sweat phenomena. In addition, it was realized that sinterability of 6061Al-$B_4C$ composite material was lowered with increasing $B_4C$ content, resulting in the decrease in its real density and at the same time in the increment of porosity.

기계적 밀링 공정에 의해 제조된 Al-B₄C 복합분말의 밀링 거동 연구

홍성모,박진주,박은광,이민구,이창규,김주명,이진규,Hong, Sung-Mo,Park, Jin-Ju,Park, Eun-Kwang,Lee, Min-Ku,Rhee, Chang-Kyu,Kim, Ju-Myoung,Lee, Jin-Kyu 한국분말야금학회 2012 한국분말재료학회지 (KPMI) Vol.19 No.4

In the present work, Al-$B_4C$ composite powders were fabricated using a mechanical milling process and its milling behaviors and mechanical properties as functions of $B_4C$ sizes ( $100{\mu}m$, 500 nm and 50 nm) and concentrations (1, 3 and 10 wt.%) were investigated. For achieving it, composite powders and their compacts were fabricated using a planetary ball mill machine and magnetic pulse compaction technology. Al-$B_4C$ composite powders represent the most uniform dispersion at a milling speed of 200 rpm and a milling time of 240 minutes. Also, the smaller $B_4C$ particles were presented, the more excellent compositing characteristics are exhibited. In particular, in the case of the 50 nm $B_4C$ added compact, it showed the highest values of compaction density and hardness compared with the conditions of $100{\mu}m$ and 500 nm additions, leading to the enhancement its mechanical properties.

Enhanced strength and ductility in particulate-reinforced aluminum matrix composites fabricated by flake powder metallurgy

Kai, X.Z.,Li, Z.Q.,Fan, G.L.,Guo, Q.,Xiong, D.B.,Zhang, W.L.,Su, Y.S.,Lu, W.J.,Moon, W.J.,Zhang, D. Elsevier Sequoia 2013 Materials science & engineering. properties, micro Vol.587 No.-

Reinforcement agglomeration always leads to severe stress concentration and porosity, which is detrimental to the deformation ability and mechanical properties of particulate-reinforced metal matrix composites. In this study, uniform distribution of 32vol%B<SUB>4</SUB>C has been achieved in B<SUB>4</SUB>C/Al composite by means of flake powder metallurgy (Flake PM), in which flake Al powder is used as the starting material. The flake Al powder exhibits higher apparent volume than spherical powders of the same mass, and thus can provide more space to accommodate the B<SUB>4</SUB>C particles. Therefore, compared with conventional PM, Flake PM can lead to more uniform distribution of B<SUB>4</SUB>C particles in the composite powder as well as in the consolidated composite. Meanwhile, the flake Al powder has a nano skin of Al<SUB>2</SUB>O<SUB>3</SUB>, which could be fractured and dispersed inside the fine matrix grains during consolidation, and were found to induce a higher normalized strain hardening rate for the composite during deformation. As a result, the Flake PM 32vol%B<SUB>4</SUB>C/Al composite exhibits an ultimate tensile strength of 305MPa and a uniform elongation of 6.6%, 63% stronger and 13% more ductile than its counterpart fabricated by conventional PM.

Effect of hybrid ceramic addition on Al7075 for prompt utilization

P. Sathiamurthi,K.S. Karthi Vinith,A. Sivakumar,N. Bagath Singh 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.3

In recent engineering applications, lightweight aluminium composites are becoming more popular as an alternative for ferrousmetals. The high cost of component manufacture has kept particulate metal matrix composites from being widely used inengineering applications. The goal of this research is to characterize stir cast Al-7075/B4C/Si3N4 reinforced hybrid composites. Hard ceramic reinforcements increase the microstructure, mechanical, and wear qualities of the material. B4C and ZrB2particles were incorporated into the Al matrix at different weight percents, such as 2, 4, 6, and 8. The microstructure, andproperties of mechanical as well as wear of ZrB2 and B4C particle composition were examined. In addition, SEM and XRDwere used to investigate the castings' morphology. As a result, hardness and strength rise as the amount of B4C-ZrB2 in thecomposite increases. The Al7075 + 8% B4C + 1% ZrB2 composite outperform all the considered composition. Furthermore,with increasing sliding distances, the specific wear rate increases and the coefficient of friction decreases. Because of itsoutstanding mechanical and wear properties, the hybrid Al7075-B4C-ZrB2 material is the excellent choice of upper wingrequirements.

Characterization and Tribological Properties of Novel AlCu4.5SiMg Alloy–(B4C/TiO2/nGr) Quaternary Hybrid Composites Sintered via Microwave

Mehmet Ayvaz 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.3

In the future, hybrid aluminum matrix composites, which are the second generation composites, will be replaced by solidreinforced third-generation quaternary hybrid composites in which nano- and micro-scale reinforcement particles are usedtogether. In this study, microwave sinterability of B4C,TiO2(nm + μm), and nGr reinforced quaternary hybrid compositesthat had AlCu4.5SiMg alloyed Matrix, and their microstructural and tribological properties after sintering were examined. The proportion of nGr in the composite sample was taken as 0.5 wt%, while B4Cand TiO2were used in three different proportions(3, 9, 12 wt%). After being compressed under 600 MPa pressure, the composite samples were sintered for 60 minat 550 °C by a microwave oven with a power of 2.9 kW and a frequency of 2.45 GHz. It was determined that due to its highmicrowave absorbency, B4Creinforcement improved the microwave sinterability more compared to TiO2. In XRD analyses,whereas Al4C3and Al3BCreaction products were not seen as harmful, the intermetallic phase of Al2Cuwas detected. Itwas determined that both friction coefficient and wear resistance increased as the proportion of B4Cincreased in compositesamples. In AlCu4.5SiMg–(12 wt% B4C/3 wt% TiO2/0.5 wt% nGr) quaternary hybrid composites with the highest hardness(97.6 HV), the lowest specific wear rate (0.118 mm3 Nm × 10−3) was detected.

표면복제법을 이용한 세라믹 복합재료 파괴현상의 투과전자현미경 분석

전형우,김긍호,김병호,Jun, Hyeung-Woo,Kim, Gyeung-Ho,Kim, Byung-Ho 한국현미경학회 1996 Applied microscopy Vol.26 No.4

Fracture surfaces of materials contain useful information ranging from crack path to the mechanism of fracture. Since limitation of electron transparency requires a sample in the form of thin foil for TEM observations, it is impossible to extract such information directly from the fracture surfaces. In this study, the method of surface replication from the ceramic fracture surface is employed to characterize the process of crack propagation in ceramic matrix composites using TEM analysis. The surface replica from the fracture surface in ceramic materials provides detailed surface morphology and more importantly, loosened particles on the fracture surface are collected. Electron diffraction and chemical composition analyses of these particles reveal crack path in the specimen. Furthermore, one can determine the mode of fracture by observing the fracture surface morphology from the image of replica. Two examples are given to illustrate the potential of the surface replication technique. In the first example, apparent toughness increase in $B_{4}C-Al$ composites at high strain rate is investigated by surface replication to elucidate the mechanism of fracture at different strain rates. The polytypes of SiC formed during the sintering of SiC-AlN composite and their effect on the fracture behavior of SiC-AlN composite are analyzed in the second example.