Addition Of B4C Research Articles

Effect of Boron Carbide Addition on the Strength and Physical Properties of Concrete

Concrete currently has become a conventional material in construction of nuclear reactor due to its properties such as safety, strength and economical in cost. Boron carbide (B4C) was used as additives in concrete are characterized as a good neutron absorber for nuclear reactor applications. The effect of B4C addition on physical and strength properties of concrete samples were investigated. The samples were prepared with three different weight percent (wt%) of B4C powder. The concrete slump tests of fresh concrete have been done to investigate the workability of mixtures. Free B4C mixture shows the highest workability compare to 5 and 20 wt% B4C concrete mixture. The density of 0 wt% of B4C is the lowest compared to 5 and 20 wt%. However, after 28 days curing time, the compressive strength test of 20 wt% B4C shows the highest value compare to 5 and 0 wt% B4C concrete respectively. It is obvious that up to 20 wt% B4C can be added to concrete mixture and cause significant strength increases.

Mechanical and Wear Behaviour of Aluminium Metal Matrix Hybrid Composites

An attempt has been made to develop and characterize Al2219 reinforced with B4C & MoS2 for Hybrid composites by using stir casting technique. The experiment evaluates the microstructure, density, micro hardness, tensile & dry sliding wear test. The result reveals that, the reinforcement particles are randomly & fine dispersed in matrix alloy as seen in microstructure. The density & micro hardness of Al2219 alloy is relatively low as compared to prepared hybrid composites. Tensile strength is minimum for Al2219+3% B4C+5% MoS2 and maximum for Al 2219 alloy. SEM was used for examine fracture surface of tensile specimens, this consists ductile & brittle fracture of mixed mode. The addition of B4C and MoS2 reinforcement decreases the wear rate of hybrid composites and increases the wear resistance of the composites.

The Influence of B<sub>4</sub>C on the Fluidity of Ti-6Al-4V-<i>x</i>B<sub>4</sub>C Composites

The fluidity of Ti-6Al-4V-xB4C composites is investigated by using a vacuum fluidity test. It is found that the solidification paths of Ti6Al-4V are changed by B4C additions. Differences in solidification processes dramatically affect the fluidity of Ti-6Al-4V-xB4C composites. With the increase of B4C additions, the fluidity of Ti-6Al-4V-xB4C composites is not monotonically decreasing, it drops to a valley initially and then increases. [doi:10.2320/matertrans.M2014142]

Processing of B4C Particulate Reinforced 6061Aluminum Matrix Composites by Melt Stirring Involving Two-step Addition

In the present work, 11wt% B4C particulate reinforced 6061 Al matrix composites were produced by conventional melt stirring method. Processing of composite is carried out at a temperature of 750°C involving two stage additions. Preheated B4C particles along with K2TiF6 halide salt (with ratio of 0.3) was introduced in steps of two rather than adding all at once. Characterization of the prepared composites is done using SEM/EDX and X-RD studies. Fairly uniform distribution of B4C particulates without clustering in 6061Al matrix was evident from SEM studies. The prepared composite consists of α-Al, B4C and minor phases like Al3Ti, AlB2 and Al3BC are confirmed by XRD studies. The addition of B4C particulates to 6061Al matrix has resulted in improvements in mechanical properties of the base alloy.

Microstructural evolution and mechanical properties of Mg composites containing nano-B4C hybridized micro-Ti particulates

In this work, the microstructural evolution and mechanical properties of extruded Mg composites containing micro-Ti particulates hybridized with varying contents of nano-B4C are investigated, and compared with Mg-5.6Ti. Microstructural characterization showed the presence of uniformly distributed micro-Ti particles embedded with nano-B4C particulates that resulted in significant grain refinement. Electron back scattered diffraction (EBSD) analyses of Mg-(5.6Ti + x-B4C)BM hybrid composites showed that the addition of hybridized particle resulted in relatively more recrystallized grains, realignment of basal planes and extension of weak basal fibre texture when compared to Mg-5.6Ti. The evaluation of mechanical properties indicated improved strength with ductility retention in Mg-(5.6Ti + x-B4C)BM hybrid composites. When compared to Mg-5.6Ti, the superior strength properties of the Mg-(5.6Ti + x-B4C)BM hybrid composites are attributed to the presence of nano-reinforcements, the uniform distribution of the hybridized particles, better interfacial bonding between the matrix and the reinforcement particles and the matrix grain refinement achieved by nano-B4C addition. The ductility enhancement obtained in hybrid composites can be attributed to the fibre texture spread and favourable basal plane orientation achieved due to nano B4C addition.

Polymerization kinetics of boron carbide/epoxy composites

This study employs Differential Scanning Calorimetry (DSC) technique and focuses on the curing kinetics and the activation energy of the commercial epoxy resin (which cures at room temperature for 12h) filled with boron carbide particles (B4C) in different amount (6 and 12wt%) and particle size (60nm, 7 and 23μm). An isothermal dwell at different temperatures (25, 35 and 50°C) was used for 180min. Thereafter, the temperature is increased by 5°Cmin−1 up to 200°C to complete the curing process. Conversion degree is calculated by combining both methods.The kinetic constant and the reaction order are calculated using Kamal's equation with diffusion control. Consequently, the activation energy is computed assuming Arrhenius’ equation.The results show a significant influence of the temperature on the reaction mechanism. Furthermore, polymerization kinetics is affected by B4C additions depending on the amount and size of the added particles.

Effects of sintering temperature and addition of Fe and B4C on hardness and wear resistance of diamond reinforced metal matrix composites

The effects of sintering temperature and addition of Fe instead of Co into the matrix composition on the mechanical properties of diamond-reinforced MMC’s have been studied. Diamond-reinforced MMC’s based on Fe-Co compositions with and without boron carbide (B4C) have been processed. Three different matrix composites (with different Fe/Co ratios) have been produced with and without B4C at a pressure of 25 MPa and sintered in N2 at various temperatures (800, 900, and 1000°C). After sintering, mechanical properties of the resultant composites have been studied and the results discussed. Addition of B4C has been found to improve the hardness and wear resistance of the composites. Optical microscopy, SEM and EDS have been used to examine the microstructure and surface of the synthesized composites.

The Effect of Al<sub>2</sub>O<sub>3</sub>-SiC and B<sub>4 </sub>Cadditions on Mechanical Properties of Cusnmatrix Composites for Cutting Tools

Keywords: Boron Carbide; Silisium Carbide; Composite; Powder Metallurgy. Abstract : In this study, effect of boron carbide (B4C), aluminium oxide (Al2O3) and silisium carbide (SiC) addition on microstructure and mechanical properties of diamond cutting segments was investigated. The effects of reinforcement particle additions on characteristic of CuSn matrix composites have been investigated. For this purpose, Al2O3, SiC and B4C addition quantity was added as 2 wt.%. Samples of segments were processed by cold pressing at 550 MPa, followed by sintering at 850°C/30min. Micro-structural aspects were observed by optical microscope. Density, hardness and wear tests were also performed. Wear behaviour and hardness values of segments changed depending on aluminium oxide, silisium carbide and boron carbide addition. The alloy CuSn– 2 wt.%. B4C presented the best results, available for use in cutting tools.

The Effect of B<sub>4</sub>C Additions on Mechanical Properties of Fe-Cu-Co Matrix Composites for Diamond Tools

The effects of boron carbide (B4C) additions on characteristic of diamond impregnated Fe-Co-Cu matrix composites have been investigated using powder metallurgy (PM) method. For this purpose, samples of Fe-(30-60)wt. % Cu–20 wt. %Co alloys and1wt. % B4C additions of its matrix were processed by cold pressing at 350 MPa, followed by sintering at 1100°C. Microstructural examination, hardness and wear tests were performed.The microstructure of Fe–Cu–Co alloys was very sensitive to the Cu content and pore closure took place with increasing the Cu content.In addition, the addition of B4C particles increased Fe–Cu-Co hardness about 44% compared to samples without B4C particles. The experimental results showed that alloy Fe–60 wt. % Cu–20 wt. %Co-1 wt. % B4C presented the best results for use in diamond cutting tools.

Microstructural Development of Fe–Cr–C and B4C Powder Alloy Coating on Stainless Steel by Plasma-Transferred Arc Weld Surfacing

The present investigation discusses the effects of B4C addition on the morphologies of primary carbides and eutectic colonies in Fe–Cr–C weld-surfacing alloys. Results reveal that a series of Fe–Cr–C weld-surfacing alloys with different B4C contents are successfully fabricated onto AISI 316 stainless steel by plasma-transferred arc welding. The microstructure of the coatings is mainly γ-Fe,Ni eutectic matrix, and hexagonal M(=Cr, Fe)7(C,B)3 and M(=Cr, Fe)23(C,B)6 carbides are non-uniformly distributed in the eutectic matrix. The average microhardness of the cladding coating is 820HV, which is almost five times of that of the AISI 316 stainless steel substrate (180HV). The maximum microhardness value of the coating is about 1,280HV. Higher current levels have resulted in higher dilution levels and also in melting/burning of the substrate.

The Influence of B<sub>4</sub>C on Mechanical Properties of MgO-SiC Based Refractory Castables

The effects of B4C addition on the room temperature physical properties and hot mechanical properties of MgO-SiC based refractory castables were investigated using magnesia and SiC fines as starting materials and silica fume as a binder. The microstructure was characterized by scanning electron microscopy (SEM). The results showed that drying strength of MgO-SiC based castables decreased with the increase in B4C addition, the immediate temperature strength and hot temperature strength increased. The HMOR at 1400°C for 0.5h decreased. This is because B4C oxidized and produced a liquid phase during heating, contributing to sintering and making the material denser. So the cold strength increased. On the other hand, due to the formation of liquids, direct binding reduced and the HMOR decreased

Al/B<sub>4</sub>C Laminated Composite Fabricated by Powder Metallurgy Process and its Mechanical Property

A new type of laminated composite with B4C particle reinforced Al matrix composites as its inner layer and metal Al as outer layer was fabricated by powder metallurgy process. The effects of sintering time on the density and the mechanical properties of Al/B4C laminated composites were investigated. In the inner layer, Vicker’s hardness was enhanced with the addition of B4C. With the extension of sintering time from 2h to 4h at 300°C, aggregation of B4C particles reduced, while the density and Vicker’s hardness improved.

An investigation of the microstructure and mechanical properties of B4C reinforced PM magnesium matrix composites

Due to their excellent properties such as high specific stiffness, strength/weight ratio, and wear resistance, metal matrix composites (MMCs) with particulate reinforcement and related manufacturing methods have become important research topics in recent years. Magnesium MMCs are materials that are commonly used for fabrication of light-weight functional components. Magnesium MMCs that are reinforced with various fractions of B4C (3, 6, and 9 wt.%) were fabricated by powder metallurgy (PM) technique using a sintering cycle in a vacuum furnace at 590°C for 9 h. A qualitative analysis of X-ray diffraction (XRD) patterns indicated the formation of Al2O3, MgO, and MgB2 phases in the structure of Mg/B4C MMCs. The sintered density of the MMCs decreased with an increase in the amount of B4C addition. The hardness of the MMCs was found to be higher than that of unreinforced Mg. The compressive test results also showed a significant effect of 3 wt.% B4C content on the compressive strength of magnesium MMCs manufactured by the PM technique.

Comparison of microstructural and mechanical properties of Al–TiC, Al–B4C and Al–TiC–B4C composites prepared by casting techniques

In the present work, production of Al–10%TiC, Al–10% B4C, Al–5%TiC–5%B4C (volume fraction) composites by casting techniques were studied. However, casting techniques suffers from poor incorporation and distribution of the reinforcement particles in the matrix. These problems become especially significant as the reinforcement size decreases due to greater agglomeration tendency and reduced wettability of the particles with the melt. Microstructure characterization of the composite samples was investigated by using scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and X-ray diffractometer (XRD).The results showed heat treatment of B4C particles and addition of TiC particles with the flux improved the wettability and incorporation of reinforcement particles into melt. Mechanical characterization of samples showed that maximum hardness had belonged to Al–5%TiC–5%B4C composite, maximum yield and tensile strength had belonged to Al–10%B4C composite and maximum elongation had belonged to Al–10%TiC composite. Furthermore, wear properties of composites revealed the better behavior for Al–B4C composite.

The Electrical Resistivity of B4C Modified Phenol-Formaldehyde Resin Matrix Composite Materials Pyrolyzed at Different Temperatures

The electrical resistivity is studied when B4C modified phenol-formaldehyde (PF) resin is heat-treated at temperatures of 300-1500 °C, and then the X-ray diffraction (XRD) spectra are also investigated. The results indicate that the electrical resistivity is elevated with the increase of pyrolytic temperature of PF resin. The addition of B4C decreases the electrical resistivity efficiently when the temperature is range of 700-1000 °C. Especially the composite is treated at tmperatures of 1000-1500 °C. The analysis of XRD spectra suggests that the addition of B4C promotes the arrangement of residue at high temperature. The arrangement reaction has not a direct effect on the electrical resistivity.

Attenuation Ratios of Cement-Based Materials Containing B<sub>4</sub>C to 14.8MeV Neutron

Cement-based material samples having 0%, 5%, 10% and 20% B4C concentrations have been prepared for this reserach. Neutron attenuation measurement has been done by using 14.8MeV neutrons from the 5SDH-2 accelerator, and some mechanics properties of the same proportion also have been tested. It has been shown that when the B4C precentage and thickness of the samples increase, neutron attenuation values of the samples increase. Both the flexural and compressive strength firstly increased with B4C addition up to 10% approximately, and then decreased sharply with an addition up to 20%. It is thus possible to enhance the neutron shielding property of cement-based materials by adding B4C.

Formation of porous SiC ceramics via recrystallization

In this study, porous SiC ceramics with interconnected huge plate-like grains were fabricated from oxidized β-SiC powder with 1 wt% B4C. When the β–α SiC phase transformation occurred at 2100 °C, rapid grain growth of α-SiC consumed the unstable β-SiC matrix resulting in an interconnected network structure with huge plate-like grains. The oxidation of β-SiC powder and the addition of B4C are necessary conditions for rapid grain growth. The observed results are discussed based on thermodynamic considerations. The measured porosity of the specimens sintered at 2100 °C for 30 min was 47% and the mean pore size was 6–7 μm. The strength of the sintered specimen was 45 ± 5 MPa.

The influence of B4C and MgB2 additions on the behavior of MgO–C bricks

Carbon-containing refractory materials have received great attention over the last years due to their importance in the steelmaking process. The oxidation of carbon present in refractory materials at temperatures above 500°C is usually accompanied by the decrease of their mechanical strength and chemical resistance. Aiming to improve the oxidation resistance of carbon-oxide refractories, the use of materials known as antioxidants has been extensively studied. In this work we evaluated the performance of MgB2 and B4C antioxidants when incorporated into MgO–C bricks. We observed that the co-addition of metallic antioxidants and B4C or MgB2 leads to refractory bricks with enhanced hot modulus of rupture and resistance against oxidation and slag corrosion. However, the excessive addition of these antioxidants could impair the performance of the obtained bricks. Thus, when determining the optimum concentration of MgB2 and B4C to be added into MgO–C refractories, one must take into consideration this behavior.

Residual strength of hot pressed zirconium diboride (ZrB2) after exposure to high temperatures

ZrB2 with different amounts of B4C additive (0-5 wt.%) has been hot pressed at 2000 degrees C and 25 MPa for 1 h. By addition of B4C, density as well as micro-hardness increased. For lower B4C content (0.5 and 1 wt.%), hot pressed ZrB2 shows considerable improvement in flexural strength after exposure in air at 1000 C for 5 h, while higher B4C content (3 and 5 wt.%) leads to marginal or no improvement. For any content of B4C, flexural strength after exposure in air at 1500 degrees C for 5 h is lower than as-hot pressed ZrB2. (C) 2011 Elsevier B.V. All rights reserved.

Fabrication and thermal shock resistance of HfB2-SiC composite with B4C additives

A HfB2 based ceramic matrix composite containing 20 vol.% SiC particles with 2 vol.% B4C as sintering additives was fabricated by hot-pressed sintering. The microstructure and properties, especially the thermal shock resistance of the composite were investigated. Results showed that the addition of B4C improved the powder sinterability and led to obtaining nearly full dense composite. The flexural strength and fracture toughness of the composite were 771 MPa and 7.06 MPam1/2, respectively. The thermal shock resistance tests indicated that the residual strength decreased significantly when the thermal shock temperature difference was higher than 600 °C. The large number of microcracks on the sample surface was the main reason for the catastrophic failure.