Boron carbide (B4C) is highly significant in the production of lightweight protective materials when added to aluminum owing to its exceptional mechanical properties. In this study, a method for fabricating Al-B4C composites using high-energy ball milling and directed energy deposition (DED) is presented. Al-4 wt.% B4C composites were fabricated under 21 different laser conditions to analyze the microstructure and mechanical properties at different values of laser power and scan speeds. The composites fabricated at a laser power of 600 W and the same scan speed exhibited the highest hardness and generated the fewest pores. In contrast, the composites fabricated at a laser power of 1000 W exhibited the lowest hardness and generated a significant number of large pores. This can be explained by the influence of the microstructure on the energy density at different values of laser power.

Al-B4C neutron absorbers are currently widely used to maintain the subcriticality of both wet and dry storage facilities of spent nuclear fuel (SNF), thus long-term and high-temperature material integrity of the absorbers has to be guaranteed for the expected operation periods of those facilities. Surface corrosion solely has been the main issue for the absorber performance and safety; however, the possibility of irradiation-assisted degradation has been recently suggested from an investigation on Al-B4C surveillance coupons used in a Korean spent nuclear fuel pool (SFP). Larger radiation damage than expectation was speculated to be induced from 10B(n, α)7Li reactions, which emit about a MeV α-particles and Li ions. In this study, we experimentally emulated the radiation damage accumulated in an Al-B4C neutron absorber utilizing heavy-ion accelerator. The absorber specimens were irradiated with He ions at various estimated system temperatures for a model SNF storage facility (room temperature, 150, 270, and 400°C). Through the in-situ heated ion irradiation, three exponentially increasing level of radiation damages (0.01, 0.1, and 1 dpa or displacement per atom) were achieved to compare differential gas bubble formation at near surface of the absorber, which could cause premature absorber corrosion and subsequential 10B loss in an SNF storage system. An extremely high radiation damage (10 dpa), which is unlikely achievable during a dry storage period, was also emulated through high temperature irradiation (350°C) to further test the radiation resistance of the absorber, conservatively. The irradiated specimens were characterized using HR-TEM and the average size and number density of radiation-induced He bubbles were measured from the obtained bright field (BF) TEM micrographs. Measured helium bubble sizes tend to increase with increasing system (or irradiation) temperature while decrease in their number density. Helium bubbles were found from even the lowest radiation damage specimens (0.01 dpa). Bubble coalescence was significant at grain boundaries and the irradiated specimen morphology was particularly similar with the bubble morphology observed at the interface between aluminum alloy matrix and B4C particle of the surveillance coupons. These characterized irradiated specimens will be used for the corrosion test with high-temperature humid gas to further study the irradiation-assisted degradation mechanism of the absorber in dry SNF storage system.

B4C/Al composite is mainly used for neutron absorbing materials, which is one of the components of equipment that manages spent nuclear fuel. There are various processes for manufacturing neutron absorbing materials, but most of them are based on the powder metallurgy. In this study, B4C/Al composite in which the reinforcement was uniformly dispersed was manufactured by using the stir casting process. The microstructure, thermal neutron absorption rate, mechanical properties and dispersibility of the reinforcement of the prepared B4C/Al composite were analyzed.

In this study, for thermal neutron absorption, an aluminum metal composite in which B4C particles were uniformly dispersed was prepared using stirring casting and hot rolling processes. The microstructure, thermal neutron absorption rate, mechanical properties and dispersibility of the reinforcement of the prepared B4C/Al composite were analyzed. The composite in which the 40 μm sized B4C particles were uniformly dispersed increased the tensile strength as the volume ratio of the reinforcement increased.

In this study, binderless-WC, WC-6 wt%Co, WC-6wt% 1 and 2.5 B4C materials are fabricated by spark plasma sintering process (SPS process). Each fabricated WC material is almost completely dense, with a relative density up to 99.5 % after the simultaneous application of pressure of 60 MPa. The WC added Co and Co-B4C materials resulted in crystalline growth. The WC with HCP crystal structure has respective interfacial energy (basal facet direction: 1.07 ~ 1.34 J·m−2, prismatic direction: 1.43 ~ 3.02 J·m−2) that depends on the grain growth direction. It is confirmed that the continuous grain growth, biased by the basal facet, which has relatively low energy, is promoted at the WC/Co interface. As abnormal grain growth takes place, the grain size increases more than twice from 0.37 to 0.8 um. It is found through analysis that the hardness property also greatly decreases from about 2661.4 to 1721.4 kg/mm2, along with the grain growth.

The effects of B4C on the mechanical properties of WC/Ni-Si hardmetal were analyzed using sintered bod- ies comprising WC(70-x wt.%), Ni (28.5 wt.%), Si (1.5 wt.%), and B4C (x wt.%), where 0 x 1.2 wt.%. Samples were prepared by a combination of mechanical milling and liquid-phase sintering. Phase and microstructure character- izations were conducted using X-ray diffractometry, scanning electron microscopy, and electron probe X-ray micro anal- ysis. The mechanical properties of the sintered bodies were evaluated by measuring their hardness and transverse rupture strength. The addition of B4C improved the sinterability of the hardmetals. With increasing B4C content, their hardness increased, but their transverse rupture strength decreased. The changes of sinterability and mechanical properties were attributed to the alloying reaction between B4C and the binder metal (Ni, Si). ≤ ≤

In the present work, 6061 Al-B4C sintered composites containing different B4C contents were fabricated and their characteristic were investigated as a function of sintering temperature. For this, composite powders and their compacts with B4C 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 660o C. Above sin- tering temperature of 640o C, real density was decreased due to the occurrence of sweat phenomena. In addition, it was realized that sinterability of 6061Al-B4C composite material was lowered with increasing B4C content, resulting in the decrease in its real density and at the same time in the increment of porosity.

In the present work, Al- composite powders were fabricated using a mechanical milling process and its milling behaviors and mechanical properties as functions of sizes ( , 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- composite powders represent the most uniform dispersion at a milling speed of 200 rpm and a milling time of 240 minutes. Also, the smaller particles were presented, the more excellent compositing characteristics are exhibited. In particular, in the case of the 50 nm added compact, it showed the highest values of compaction density and hardness compared with the conditions of and 500 nm additions, leading to the enhancement its mechanical properties.

Mechanical coating process was applied to form 89 %-hydrolyzed poly vinyl alcohol (PVA) onto boron carbide (B4C) nanopowder using one step high energy ball mill method. The polymer layer coated on the surface of B4C was changed to glass-like phase. The average particle size of core/shell structured B4C/PVA was about 50 nm. The core/shell structured B4C/PVA was formed by dry milling. However, the hydrolyzed PVA of 98~99% with high glass transition temperature (Tg) was rarely coated on the powder. The Tg of polymer materials was one of keys for guest polymer coating on to the host powder by solvent free milling.

Carbon-ceramic composites refer to a special class of carbon based materials which cover the main drawbacks of carbon, particularly its proneness to air oxidation, while essentially retaining its outstanding properties. In the present paper, the authors report the results of a systematic study made towards the development of C-SiC-B4C composites, which involves the effects of compositional parameters, namely, carbon-to-ceramic and ceramic-to-ceramic ratios, on the oxidation behaviour as well as other characteristics of these composites. The C-SiC-B4C composites, heat-treated to 1400℃, have shown that their oxidation behaviour at temperatures of 800~1200℃ depends jointly on the total ceramic content and the SiC : B4C ratio. Good compositions of C-SiC-B4C composites exhibiting zero weight loss in air at temperatures of 800~1200℃ for periods of 4~9 h, have been identified. Composites with these compositions undergo a weight gain or a maximum weight loss of less than 3% during the establishment of a protective layer at the surface of carbon in a period of 1~6 h. Significant improvement in the strength of C-SiC-B4C composites has been observed which increases with an increase in the total ceramic content and also with an increase in the SiC : B4C ratio.

The effects of boron or manganese added as , Mn, , B on TiC-30vo1.% cermet sintered at 1380 and for 1 hour, were examined in relation with shrinkage, relative density, microstructure, lattice parameter, hardness and fracture toughness (). The results are summarized as follows: 1) The highest shrink-age showed about 30.5% in the specimen added BC and the maximum relative density was about 99% in the specimen added ; 2) The grains of TiC were grown during sintering and made the surrounding structure by adding boron and manganese. The largest grain size showed about in the specimen with boron sintered at ;3) The lattice parameter of TiC was about and about by adding other elements; 4) The highest hardness was about in the specimen with B4C; 5) The fracture toughness () showed about in the specimen added .

자체연소반응법에 의하여 탄화붕소(B4C)를 합성함에 있어서 자체적으로는 반응이 이루어지지 않아서 간접점화법인 화학로법(Chemical Furnace)으로 합성을 하였으며, 성형압력과 몰비를 변수로 하여 연소온도 및 연소속도의 변화를 측정하였다. 성형밀도가 이론밀도의 70%에서 연소온도와 연소속도가 가장 높았으며, 몰비에 대한 영향은 표준비였을 때 연소온도와 연소속도가 가장 높았다. 그리고 성형밀도에 따른 입자의 크기변화는 성형밀도가 높을수록 입자의 크기는 작아졌으며 따라서 비표면적은 커졌다.