Addition Of B4C Research Articles

One-step preparation of bi-layer foamed glass-ceramics using asynchronous oxidization of SiC and B4C

Bi-layer foamed glass-ceramic has the advantages of both dense and foamed structure which lead to low bulk density and high mechanical strength. We propose a new one-step method to produce bi-layer foamed glass-ceramic using the asynchronous oxidization of B4C and SiC. The parent glass is prepared by melting-quenching method, followed by foaming through powder sintering route with addition of B4C and SiC. The bi-layer structure and formation of bi-layers are investigated by scanning electron microscope (SEM), X-ray computed tomography, 11B NMR, and high temperature melting observation system (HTMOS). The results show that during the sintering process, the oxidization of B4C in top layer at low temperature forms boron oxide and helps the formation of glass melt in the top layer. The oxidization of SiC at high temperature leads to foaming in the top layer. The prepared bi-layer foamed glass-ceramic has low bulk density of 1.06 g·cm−3 and high flexural strength of 26.15 MPa.

Enhancing Surface Properties of Cu-Fe-Cr Alloys through Laser Cladding: The Role of Mo and B4C Additives

Laser cladding is a powerful surface treatment technique that can significantly enhance the properties of metal alloys. This study delves into the liquid phase separation behavior of Cu-Fe-Cr alloys under the rapid solidification conditions inherent in laser cladding and evaluates the influence of 4% Mo and 2% B4C additions on the resulting alloy characteristics. The intensive undercooling characteristic of the laser cladding process facilitates the alloy’s entry into the liquid-phase immiscibility gap, prompting pronounced phase separation. Our investigation reveals the emergence of Fe-rich regions, exhibiting a variety of shapes, set against a continuous Cu-rich matrix. The incorporation of Mo and B4C was found to modulate the mixing enthalpy and entropy, thereby refining the phase distribution: Mo was observed to prevent the agglomeration of Fe cores, resulting in a dispersion of isolated Fe cores throughout the Cu-rich matrix, while B4C promoted a more uniform compositional distribution. This study further enumerates the enhancements in microhardness, wear resistance, and magnetic properties of the alloys. Notably, the Cu-Fe-Cr-Mo-B4C alloy demonstrated a microhardness exceeding 600 HV, a low coefficient of friction around 0.15, high saturation magnetization, and reduced coercivity. These results underscore the efficacy of laser cladding in tailoring the microstructure and properties of Cu-Fe alloys, providing insights for the controlled manipulation of phase separation to optimize surface characteristics for engineering applications.

Microstructure and Mechanical Properties of In Situ Synthesized Metastable β Titanium Alloy Composite from Low-Cost Elemental Powders

The titanium matrix composite was produced through a hot compaction process at 1250 °C using the mixture of elemental powders with chemical composition of Ti-5Al-5Mo-5V-3Cr and 2 wt.% addition of boron carbide. The phase analysis via X-ray diffraction method was performed to confirm the occurrence of an in situ reaction between boron carbide and titanium. Then, the wide-ranging microstructural analysis was performed using optical microscopy as well as scanning electron microscopy along with energy-dispersive X-ray spectroscopy and electron backscatter diffraction. Based on this investigation, it was possible to describe the diffusion behavior during hot compaction and possible precipitation capabilities of TiC and TiB phases. Tensile and compression tests were conducted to determine the strength properties. The investigated composite has an ultimate tensile strength of about 910 ± 13 MPa with elongation of 10.9 ± 1.9% and compressive strength of 1744 ± 20 MPa with deformation of 10.5 ± 0.2%. Observation of the fracture surface allowed us to determine the dominant failure mechanism, which was crack propagation from the reaction layer surrounding remaining boron carbide particle, through the titanium alloy matrix. The study summarizes the process of producing an in situ titanium matrix composite from elemental powders and B4C additives and emphasizes the importance of element diffusion and reaction layer formation, which contributes to the strength properties of the material.

Microstructure and mechanical properties of in-situ B4C reinforced TC4 composites prepared by laser melting deposition

In order to satisfy the increasingly harsh service environments of modern aircrafts, the novel in-situ reinforced xB4C/TC4 (x = 0–1.5 wt%) composites were prepared by laser melting deposition (LMD) and their microstructure, mechanical properties were investigated. The dual reinforcement phases of TiC and TiB were formed after B4C addition. A more favorable microstructure of refined α-Ti grains and uniformly-distributed reinforcement phases was obtained after adding 0.5 wt% B4C. The 0.5B4C/TC4 composite exhibited a moderate anti-abrasion ability owing to its beneficial microstructure and relatively high microhardness. Furthermore, it possessed the highest strength due to the effects of grain strengthening and dispersion strengthening induced by the (TiC + TiB) phases. This work provides theoretical basis and technical guidance for the development of high-performance Ti matrix composites.

Effects of boron source on properties of pressureless solid-state sintered silicon carbide ceramics

The effects of the boron source (B, BN, and B4C) on the thermal, electrical, and mechanical properties of pressureless solid-state sintered SiC ceramics were investigated. A high relative density of 99.9 % was successfully achieved for all ceramic specimens using an appropriate additive composition and ideal sintering conditions. SiC ceramics sintered with B and B4C additives displayed higher electrical and thermal conductivities and higher flexural strength than those sintered with the BN additive at the same relative density. The presence of intrinsically-weak, electrically-insulating BN grains at the junction and grain boundaries increased both the fracture toughness and electrical resistivity, while the flexural strength and thermal conductivity of the ceramics decreased. The electrical resistivity, thermal conductivity, and flexural strength of the SiC ceramics were able to be adjusted with values ranging from 3.2 × 104–1.6 × 106 Ω‧cm, 72.4–147.5 W‧m−1‧K−1, and 386–545 MPa, respectively, depending on the boron source used.

Effect of B4C on microstructure evolution and high-temperature mechanical properties of TiAl matrix composites

This study synthesized and characterized the Ti-48Al-2Cr-2 Nb-based composite reinforced by B4C addition, which was produced by spark plasma sintering. The grain size of composites decreased significantly from 225 ± 5 µm to 51 ± 5 µm with the increase of B4C content, mainly due to the pinning effect of in-situ generated TiB2 and Ti2AlC particles at grain boundaries, which limited the rapid grain growth of the matrix. With the addition of B4C, the volume fraction of Ti2AlC increased from 3.0% to 7.4%, with an average size of approximately 5 µm. The ultimate tensile strength and total fracture elongation of the Ti-48Al-2Cr-2 Nb alloy were 482.9 MPa and 10.2% at 800 ℃, correspondingly. With 0.3 wt% addition of B4C, B4C/Ti-48Al-2Cr-2 Nb composite exhibited superior strength (579.5 MPa) and ductility (12.6%) at the same tensile temperature. The reinforced strength of the composite was mainly attributed to the grain refinement and precipitation strengthening.

Ultrafast high-temperature sintering (UHS) of ZrB2-based materials

ZrB2 is one of the most promising materials for extreme environment applications, especially in the aerospace field, due to the combination of superior thermophysical properties and low density. Nevertheless, pure ZrB2 is intrinsically hard to sinter, requiring either the application of intense external pressure or the use of sintering aids. In the present work, the feasibility of ultrafast high-temperature sintering (UHS) for the densification of commercial ZrB2 was explored. Thanks to the addition of B4C as a sintering aid, Densities up to 92–98% could be obtained in just 2 min. Hardness of 16.3–17.8 GPa was obtained for the UHS ZrB2-based ceramics, similar to what is reported in the literature using slower, more sophisticated and energy-consuming sintering approaches like spark plasma sintering. These first results show that UHS could provide a quick and simple way to produce high-performance ZrB2-based components with just a few minutes of processing time in pressure-less conditions.

The Effect of Hybrid B4C and Si3N4 Nanoparticles on the Mechanical and Physical Properties of Copper Nanocomposites

This study investigated the effects of reinforcing pure copper with hybrid B4C and Si3N4 nanoparticles on the mechanical and physical properties of the nanocomposite matrix. The composite matrix was prepared using the powder metallurgy (PM) method, allowing uniform nanoparticle dispersion within the copper matrix. The PM method was a practical approach for achieving a homogeneous and good dispersion of the reinforcing particles in the matrix while controlling the porosity and improving the microstructure of the fabricated composite matrix. The addition of B4C and Si3N4 are both very hard and dense materials. When added to a material, they can fill voids and reduce porosity. This can lead to significant improvements in the material’s mechanical properties. The study found that adding hybrid B4C and Si3N4 nanoparticles enhanced the microhardness and mechanical properties of the nanocomposites. The improvements in the mechanical and physical properties of such composites containing 5% B4C were 21.6% and 18.4% higher than the copper base alloy. The findings suggest that including ceramic particles is a viable strategy for enhancing the mechanical characteristics of copper in its pure form. For example, adding 5% B4C particles to copper resulted in a 23% increase in Young’s modulus of the material while reducing electrical conductivity by 4.6%. On the other hand, the hybrid composite Cu/5%B4C + 2.5%Si3N4 showed a 32% improvement in Young’s modulus and 71% in the microhardness value compared to the base metal. This makes it a promising option for various engineering applications, such as high-performance electrical contacts and bearings.

Mechanical and Structural Characterization of Laser-Cladded Medium-Entropy FeNiCr-B4C Coatings.

Equiatomic medium-entropy alloy (MEA) FeNiCr-B4C (0, 1, and 3 wt.% B4C) coatings were deposited onto an AISI 1040 steel substrate using pulsed laser cladding. Based on an SEM microstructural analysis, it was found that the cross-sections of all the obtained specimens were characterized by an average coating thickness of 400 ± 20 μm, a sufficiently narrow (100 ± 20 μm) "coating-substrate" transition zone, and the presence of a small number of defects, including cracks and pores. An XRD analysis showed that the formed coatings consisted of a single face-centered cubic (FCC) γ-phase and the space group Fm-3m, regardless of the B4C content. However, additional TEM analysis of the FeNiCr coating with 3 wt.% B4C revealed a two-phase FCC structure consisting of grains (FCC-1 phase, Fm-3m) up to 1 µm in size and banded interlayers (FCC-2 phase, Fm-3m) between the grains. The grains were clean with a low density of dislocations. Raman spectroscopy confirmed the presence of B4C carbides inside the FeNiCr (1 and 3 wt.% B4C) coatings, as evidenced by detected peaks corresponding to amorphous carbon and peaks indicating the stretching of C-B-C chains. The mechanical characterization of the FeNiCr-B4C coatings specified that additions of 1 and 3 wt.% B4C resulted in a notable increase in microhardness of 16% and 38%, respectively, with a slight decrease in ductility of 4% and 10%, respectively, compared to the B4C-free FeNiCr coating. Thus, the B4C addition can be considered a promising method for strengthening laser-cladded MEA FeNiCr-B4C coatings.

A theoretical focus on nanoparticle attenuation capabilities for potential utilizations in radiation protect: TiO2-SiO2-Fe3O4-B4C-Al2O3

Radiation shielding materials are essential for various applications in space exploration, nuclear power plants, and medical devices. In this study, we present a theoretical design of radiation shielding nanocomposites based on a combination of TiO2-SiO2-Fe3O4-B4C-Al2O3 materials. Using the Phy-X/PSD, EpiXS, and XMuDAT programs, we calculated the radiation shielding properties, including mass attenuation coefficient, mean free path, and effective atomic number, of a series of nanocomposite structures with different Fe3O4 and B4C contents. Our results show that the addition of Fe3O4 and B4C to nanocomposites enhances the radiation shielding efficiency and the maximum shielding is observed in the nanocomposite with the highest density. The theoretical calculations also reveal that the proposed nanocomposites have excellent radiation shielding properties compared to conventional shielding materials, such as lead and concrete. This work demonstrates the potential of using a computational approach to design novel radiation shielding nanocomposites with improved performance, which could have significant implications for a wide range of applications.

Лейкоксеновый концентрат как эффективное сырье для получения высокотемпературных керамических композитов на основе MAX-фаз

The authors have developed a three-stage technology for making dense Ti3SiC2–TiB2–(TiC)–SiC ceramic composites of a leucoxene concentrate being a product of previous treatment of titanium-containing sandstones. The first stage means the synthesis of agglomerated Ti3SiC2–TiB2–SiC powders which may significantly differ in SiC content. The synthesis proceeds by the method of the vacuum carbosilicothermic reduction of leucoxene concentrate using SiC as a reducing agent with addition of B4C as a solid boron-containing component. The second stage is etching the obtained powders with hydrofluoric acid in order to remove the by-products of silicide composition having been formed of impurities in leucoxene concentrate. At the final third stage, the purified Ti3SiC2–TiB2–(TiC)–SiC powders are hot-pressed in a graphite die under 30 MPa at a temperature of 1500-1550 °C. The end product is Ti3SiC2–TiB2–(TiC)–SiC ceramic composites with nearly absolute pore-free microstructure.

Role of B4C in the directed energy deposition of aluminum alloy 6061/B4C composite using core-shell powder for crack annihilation, pore mitigation, and grain refinement

Despite the high demand for additive manufacturing of high-strength aluminum alloys (60XX and 70XX), high-strength aluminum alloys are one of the most difficult materials to manufacture through metal additive manufacturing (MAM) because of their high laser reflectivity, thermal conductivity, low viscosity, and large solidification range. Thus, MAM products of high-strength aluminum alloys are characterized by pores, cracks, and irregular surface morphology. In the present study, the stable MAM behavior of aluminum matrix composites was achieved by adding B4C reinforcement to the feedstock powder in the form of a novel core-shell powder. The aluminum alloy 6061, which is notorious for its difficulty in MAM, was selected as the matrix. The core-shell B4Cp/6061 MMC powder was prepared for MAM via directed energy deposition (DED). The B4C addition effectively mitigated the formation of cracks, pores, and balling during DED. In addition, the grains were refined, thus preventing anisotropy and improving the mechanical properties. Furthermore, the favorable effect of B4C addition during DED was found to be caused by the formation of AlB2 during solidification. These findings provide a basic understanding of the promising potential of MMCs fabricated by MAM.

Wear Behaviour of a Cu-Ni-Sn Hybrid Composite Reinforced with B4C prepared by Powder Metallurgy Technique

Cu matrix composites benefit from the high electrical and thermal conductivities of Cu and the mechanical wear/erosion resistance of hard reinforcement. In this study, an attempt has been made to determine the effect of the addition of reinforcement B4C in Cu-Ni-Sn. The B4C is reinforced to form a hybrid Cu matrix composite with powder metallurgy technique. The hybrid composites are obtained by milling, blending, and compacting the powders to obtain a fine grain-sized particle without aggregation. The grain size and particle nature were characterized using scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques, respectively. The microstructure, density, hardness, and wear rate of the composites were studied. The pin-on-disc method is equipped to study the wear behaviour and coefficient of friction. The sintered density of the prepared Cu-15%Ni is 98.25 %, Cu-8%Sn is 98.20 %, Cu-15%Ni-8%Sn is 98.10 % and Cu-15%Ni-8%Sn-2%B4C is 95.26 % and lower specific wear rate has been recorded for Cu-15Ni-8Sn-2B4C 121×10-6 mm3/(Nm) and the addition of reinforcement B4C in Cu-Ni-Sn displays remarkable changes in wear rate and friction coefficient.

Effect of ceramic particles on microstructure and properties of CoCrMoNbTi high-entropy alloy coating fabricated by laser cladding

In this study, CoCrMoNbTi, CoCrMoNbTi(B4C)0.2 and CoCrMoNbTi(SiC)0.2 high-entropy alloy coatings are prepared by laser cladding. These three coatings show significant differences in terms of microstructure and mechanical properties. In terms of microstructure, the Pure-HEA exhibits a uniform microstructure distribution, and the coating consists of two BCC phase-solid solution structures (BCC1 and BCC2) with different lattice constants. SiC-HEA exhibits a denser microstructure than Pure-HEA, and both coatings exhibit a typical dendritic structure. In contrast, the microstructure of B4C-HEA transformed from dendritic crystals to fully equiaxed crystals, and the grain refining effect can even up to two orders of magnitude. Both B4C-HEA and SiC-HEA are composed of BCC1, BCC2 and TiC phases, where TiC is obtained by the in-situ reaction. The effects of B4C and SiC on the mechanical properties of the high-entropy alloy are evaluated in terms of microhardness and wear resistance. The results show that B4C has the best strengthening effect on the alloy properties, the microhardness of the coating increases from 666.2 HV0.5 to 886.9 HV0.5. The room temperature wear resistance of the alloy is enhanced, and the frictional coefficient and wear rate are significantly reduced. Moreover, the wear mechanism is transformed from adhesive wear to abrasive wear due to the addition of B4C. This work provides insight into the application of ceramic particle-reinforced high-entropy alloys.

Superhard and superconductive polycrystalline boron doped diamond synthesized with different concentration of B4C

Boron doped diamond are potential superhard materials with good electric conductivity. In this work, polycrystalline boron doped diamond (p-BDD) with different boron concentration were synthesized from the mixture of graphite and boron carbide under ultra-high pressure (15 GPa) and temperature (2500–2700 K). The results indicate that no more boron atoms can be inserted into diamond when the boron concentration is above 4 at%. The EELS spectra indicated that the boron atoms have been doped into the diamond grains, and surplus boron carbide locate at the grain boundary. The hardness measurements reveal that the p-BDD doped with 1 at% and 23 at% boron atoms exhibit high hardness of 78.5 GPa and 45 GPa, respectively, which is equivalent to the hardness of single crystal diamond and cubic boron nitride. The p-BDD is a semiconductor and transforms into superconductive state below 2.5 K. According to microstructure measurements, highly dense p-BDD and B4C bonded diamond exhibit superhard behavior because of the strong bonding of diamond grains by B4C additives. The oxidation temperature of these p-BDD specimens is around 1538 K in the air, which is far higher than diamond. B4C is demonstrated as a superior additive to sinter superhard and electric conductive p-BDD, which are extremely useful in areas where high hardness and electric conductive are highly desired.

Hardness Measurements and Interface Behavior of SiC-B4C-Si Multiple Phase Particulate Composites Made with Melt Infiltration and Additive Manufacturing

Reaction-bonded SiC-B4C-Si ceramic composites were binder jet 3D-printed and subsequently pressureless-melt-infiltrated with molten Si. The addition of B4C aided the Si infiltration to produce a highly dense composite. The microstructures and phases of these composites were examined. The measured hardness values of each constituent with Vickers and nanoindentation matched the bulk values, and the macro-hardness values with Knoop and spherical indentation represented the bulk, composite hardness values of all three phases together, which was close to a rule of mixtures value. For particulate-based composites, this is a significant finding. The interfacial bonds of SiC and Si were imaged using scanning transmission electron microscopy to view intimacy, whereas the crack propagation was examined with carefully placed indents. This work demonstrated that pressureless melt infiltration with a reactive particle provides a method to shape non-wetting reaction-bonded ceramic composites with limited shrinkage and high density and provides insights into the mechanical behavior with numerous indentation techniques.

Wear resistance of surfaced modified CoCr alloy with stellite alloys and boron carbide coating via laser alloying

Resistance in joint prostheses remains widely studied in terms of wear due to the loose debris that causes the implant loosening failure. The present work aims to explore the tribological behavior of surface-modified CoCr alloy using Stellite 6 and Stellite 12 coatings with and without B4C additions created via laser surface alloying. The microstructural analysis of the laser surface alloying coatings was performed using metallographic techniques, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), atomic force microscopy (AFM), and nanoindentation tests. The tribological performance of coatings was evaluated using a pin-on-disc tribometer under dry sliding wear conditions. The experimental results showed that the Stellite 6, Stellite 12, and B4C particles were uniformly distributed in the coatings produced with the circular spot of the laser. The microstructure after laser surface alloying generates different intermetallic secondary phases as M23C6, WC, and B4C carbides, modifying the mechanical and tribological response. Tribological results of Stellite 12 with B4C additions and B4C laser surface alloying coatings showed better performance by reducing the coefficient of friction and increasing the wear resistance.

Densification and Properties of Bimodal 316L Stainless Steel Produced by Binder Jetting Printing with Addition of B4C.

Boron-based aids are commonly introduced to tackle the unsatisfactory densification of SS316L parts fabricated by binder jetting (BJ) technology. However, there is scarce study on the effect of sintering aids on the mechanical performance. This work investigates the effect of B4C aids and sintering temperature on the mechanical performance and microscopic morphology of BJ printing SS316L parts. SS316L powders with a bimodal size distribution were adopted to enhance density and reduce the shape distortion. Besides, B4C was added as a sintering aid to promote densification during sintering. The results show that the bimodal powder is in favour of the density increase and the sintering process. The sintering temperature is largely reduced with the addition of B4C. Further, the mechanical performance is mainly affected by the final density and B4C content. In view of a comprehensive evaluation of shape retention and properties, B4C content of 1 wt.% and sintering temperature of 1250°C are expected to be the optimal parameters.

Investigation of the Mechanical and Machinability Characteristics of Al6061 Composites Reinforced with B4C Particles

Abstract: Metal matrix composites especially Aluminium metal matrix has emerged as structural materials satisfying all requirements basically light weight, high strength values and high toughness values. The improved mechanical properties combined with the savings in weight have paved way for engineering applications in automotive, aerospace applications. This is due to the exhibiting superior properties compared to the base matrix. It has also replaced conventional materials when specific properties are demanded for the required applications. In the present work, successful attempts were made to reinforce Boron carbide (B4C – 4 to 10% in steps of 2%) additions using stir casting method with copper (CU) chill material embedded in mould. Mechanical properties such as UTS, hardness have been studied. Machinability studies has been carried out using turning tests. The influence of cutting parameters namely feed, speed and depth of cut has been studied with respect to the power consumption. Cutting forces were measured by varying spindle speed, feed and depth of cut. Results indicate the improvement in mechanical properties with addition of B4C and the castings made in Cu chill exhibits higher values of UTS and hardness. From the machinability studies it is observed that the power required to machine composite increases with increase in the B4C additions.

Effect of B4C addition on microstructure and tribological performance of laser cladded WC−10Co4Cr coatings

Effect of B4C addition on microstructure and tribological performance of laser cladded WC−10Co4Cr coatings