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In the presented work, a boron carbide sample with a purity of 99.9%, particle size $1$–$3\mu$m and a density of $1.8\mathrm{\text{g}}/{\mathrm{\text{cm}}}^3$ was used. Boron carbide samples were irradiated with linear electrons in the energy range of 2.5 MeV at the doses of $4.16\times 10^{16}$, $1.20\times 10^{17}$ and $1.03\times 10^{18}{\mathrm{\text{cm}}}^{-2}$ at room temperature. XRD results show that only in the crystal structure of ${\mathrm{\text{B}}}_{13}{\mathrm{\text{C}}}_2$ compound, among boron carbide samples irradiated in the dose rate from $4.16\times 10^{16}{\mathrm{\text{cm}}}^{-2}$ to $1.03\times 10^{18}{\mathrm{\text{cm}}}^{-2}$ phase transition does not occur. The observed decrease in the lattice parameter values was explained as the strengthening of the bonds as a result of the recombination of defects in the crystal by influencing electron fluence. Dynamics of Raman spectra change and analytic analysis of intensive and duplex modes in various electron fluxes in (${\mathrm{\text{B}}}_{12}$) CBC-structure were performed and the occurring disorder in Raman active has been identified.

The electronic and optical properties of pentagonal B₂C (penta-B₂C) monolayer are investigated by means of the first-principles calculations in the framework of the density functional theory. The cohesive energy consideration confirms the good stability of the B₂C nanostructure in this phase. The electronic band structure reveals that the valence band maximum (VBM) is located at $X$-point of the first Brillouin zone (BZ) whereas the conduction band minimum (CBM) is situated at the center of the BZ, resulting in an indirect energy bandgap of about 1.5 eV. Furthermore, a calculated low absorption and low reflection of the material in low energy ranges denote the transparency of the B₂C monolayer in the investigated range for normal light incidence. The obtained results may find application in fabrication of future opto-electronic devices.

Spark plasma sintering (SPS) of pure commercially sub-micron B₄C powder at 1700–1900${}^{\circ }$C for 20min has been conducted and their wear properties have been investigated by reciprocating friction and wear test. It was found that the relative density increased with the increase and the grain size increased a little at 1700–1900${}^{\circ }$C. Wear mechanisms in the temperature range of 1700–1900${}^{\circ }$C have been proposed such that at 1700${}^{\circ }$C the wear mechanism was dominated by plastic deformation and intergranular fracture, while at 1800–1900${}^{\circ }$C there was transition to the surface fracture or grain pull-out. A model for the spherical abrasive wear was proposed to describe the friction and wear of the B₄C ceramics which is well-fitting with the experimental results.

In this paper, high purity boron carbide samples were irradiated by ${}^{60}$Co gamma radioisotope source (0.27 Gy/s dose rate) with 50, 100, 150 and 200 irradiation hours at room-temperature. The unirradiated and irradiated boron carbide samples were heated from 30${}^{\circ }$C to 1000${}^{\circ }$C at a heating rate of 5${}^{\circ }$C/min under the argon gas atmosphere of flow rate 20 ml/min. Thermogravimetric (TG) and Differential Scanning Calorimetry (DSC) were carried out in order to understand the thermodynamic kinetics of boron carbide samples. The weight kinetics, activation energy and specific heat capacity of the unirradiated and irradiated boron carbide samples were examined in two parts, T$\le$ 650${}^{\circ }$C and T$\ge$ 650${}^{\circ }$C, according to the temperature. The dynamic of quantitative changes in both ranges is different depending on the irradiation time. While the phase transition of unirradiated boron carbide samples occurs at 902${}^{\circ }$C, this value shifts upto 940${}^{\circ }$C in irradiated samples depending on the irradiation time. The activation energy of the unirradiated boron carbide samples decreased from 214 to 46 J/mol in the result of 200h gamma irradiation. The reduction of the activation energy after the irradiation compared to the initial state shows that the dielectric properties of the irradiated boron carbide samples have been improved. After the gamma irradiation, two energy barrier states depending on the absorption dose of samples were formed in the irradiated samples. The first and second energy barriers occurred in 0.56–0.80 and 0.23–0.36 eV energy intervals, respectively. The existence of two energy levels in the irradiated boron carbide indicates that the point defects are at deep levels, close to the valence band.

A laboratory ultrasound technique has been developed to measure the longitudinal velocity of sound in high purity and density boron carbide and lanthanum hexaboride materials prepared by shock wave compression. Using the measured value of the longitudinal velocity of sound υ_L, we have calculated the Young's modulus E, the Bulk modulus K, the Shear modulus G and the Poisson's ratio ν. X-rays diffraction has also been carried out on these materials.

The work functions of (001) and (00-1) surfaces of B₄C are investigated with density functional theory and symmetry slab model. These two surfaces are found to be almost nonpolarized and their work functions are 5.15 eV and 5.46 eV, respectively.

Friction stir processing (FSP), which was the advancement in the friction stir welding technique, is thought to be an economic approach to alloying in the solid state that can be used to make composites. In this study, FSP was carried out to produce AA7075 (B₄$\mathrm{\text{C}}+\mathrm{\text{T}}$iN) composite by varying the composition of the reinforcement particles. Microstructural analysis was carried out and the homogenous distribution of the reinforced particles on the surface of AA7075 alloy was ensured. X-ray diffraction studies were carried out to analyze the phases present after fabricating the hybrid surface composites. Microhardness test was performed on the specimens before and after the fabrication process. Grain refinement in the friction stir processed zones was evidently seen in the optical microstructures. The combined effect of the ceramic powders and grain refinement led to increase in the microhardness in the hybrid surface composites compared with the base AA7075 plate. A 33.87% increase in microhardness was observed in the sample AA7075 reinforced with 75% B₄C and 25% TiN. Wear testing was carried out at various loads (5, 10, 15 and 20 N) and at different sliding velocities (300, 350, 400 and 450 rpm) and the track distance was maintained at 1000 m. It was observed that the highest wear rate is $3.2\times 10^{-7}$ cm³/Nm for the base plate AA7075 and the sample AA7075 reinforced with 50% B₄C and 50% TiN shows the lowest wear rate of $0.56\times 10^{-7}$ cm³/Nm. It is observed that the addition of B₄C and TiN has resulted in a significant improvement in the wear resistance of the AA7075 alloy.

Boron carbide is one of the advanced ceramic materials which is used in a wide range of applications. However, this material needs a high sintering temperature (~2200°C). Using nano-size powders for producing ceramic parts results in lowering sintering temperature and also enhances toughness and hardness of the material. One of the methods for producing ceramic nano powders is attrition milling. However, as the milling balls and wall are made of steel, some impurities specially iron will be introduced to the powder during milling. Chemical analysis of the milled powder shows that more than 33wt% of the powder consists of iron. These uncontrolled impurities affect the mechanical and physical properties of sintered ceramic parts that are made of such a powder. Therefore, these impurities must be removed from the powder. Hydro metallurgical beneficiation technique with two different solvents has been used for purification of the powder. The result of chemical analysis after purification showed that the weight percentage of iron in powder dropped to 9% and 0.8% (depending on the solvents). Moreover, the sintering behavior of hot-pressed boron carbide powder with different percentages of iron as sintering aid has been studied. The results showed excellent densification and hardness of the sintered parts.

The hardness, toughness and sum of cracks measurement of fine-grained WC-Co hard metals were studied. Thirty commercial and experimental hard metal grades with different additives such as boron carbide (B₄C), vanadium carbide (VC), chromium carbide (Cr₃C₂) and silicon carbide (SiC) were prepared in a commercial sinter HIP furnace. Physical, mechanical and microstructure properties were investigated to build up a representative hardness/sum of cracks measurement band. This band was then used to estimate the most effective sintering temperature and the amount of each additives. Afterwards, influence of grain growth inhibitors in optimum condition were compared. The results showed that the grades, doped with B₄C and VC as growth inhibitor exhibits more hardness than other comparable doped alloys. However, Cr₃C₂ is favorable in toughness improvement.