Addition Of B4C Research Articles

Microstructure and Mechanical Properties of B4C-Blended M3:2 High-Speed Steel Powders Consolidated by Sintering and Heat Treatment

Water-atomized powders of M3:2 high-speed steel (HSS) were blended with B4C and consolidated by cold press sintering. With the addition of B4C (~ 0.2 vol.%), satisfactory mechanical properties were achieved for HSS by sintering at a temperature as low as 1190 °C [e.g., 53.2 ± 0.2 in the Rockwell hardness (HRC) and 3074 ± 56 MPa in bending strength]. High relative density (98.5%) and good strength were attributed to the mechanism described as follows: First, the atoms of boron and carbon escaped after the reaction between B4C and iron matrix. Then, the sintered HSS was strengthened by boron atoms while they were distributed in M6C or MC carbides and iron matrix. Second, a plenty of M6C carbides were formed due to the release of carbon atoms. As a result, the value of solidus temperature was reduced. In addition, mechanical properties were greatly improved by heat treatment (quenching and tempering) (e.g., 61.2 ± 0.3 in HRC, 4356 ± 64 MPa in bending strength, and 42.3 ± 0.5 MPa m1/2 in fracture toughness, respectively).

Properties of heat resistant hollow glass microsphere/phosphate buoyancy materials with different coatings

The heat resistant buoyancy materials were fabricated by the molding method using the aluminum dihydric phosphate as the matrix and hollow glass microspheres as the filler, respectively. In order to improve the waterproof performance of the buoyancy, two strategies, adding the B4C additives and introducing the silica-based coatings, were adopted. The study showed that the samples with the B4C content of 10 wt% possessed the optimal comprehensive performance, such as low density (0.540 g/cm3) and low water absorption (29.6%). The effect of the coating types and coating times on the density, water absorption, compressive strength and specific strength of the buoyancy materials were also studied. After 4 times of coating, the density and the compressive strength of the sample increased to 0.62 g/cm3 and 6.0 MPa, respectively; the water absorption of the samples greatly decreased to 10%. Besides, all samples exhibited significant pseudoductility. The buoyancy materials with the above superior properties can be potentially used in the deep see fields.

Microstructure and property of laser clad Fe-based composite layer containing Nb and B4C powders

In present study, Fe-based composite layers were fabricated on steel substrate by laser cladding with or without the addition of Nb and B4C in Fe-based alloy powders. The phase composition, microstructure evolution, microhardness and wear properties of Fe-based composite layers were studied. The results showed that the phases in the Fe-based composite layer were mainly α-Fe, Fe2B, Cr7C3 and Cr23C6. The addition of Nb and B4C resulted in the in-situ formation of NbC phase, an increase in the amount of Fe2B phase, and the refinement of the microstructure in the Fe-based composite layer. The microhardness of the Fe-based composite layer was increased by 269.5 HV0.5 and the wear resistance was improved to about 1.5 times the original wear resistance when the 5% Nb and 5% B4C powders were added. The wear mechanisms of both two Fe-based composite layers were abrasive wear and adhesive wear.

Vpliv dodatka B4C na mikrostrukturo, trdoto in suho drsno obrabo vroče stiskanih kompozitov AZ91

Vpliv dodatka B4C na mikrostrukturo, trdoto in suho drsno obrabo vroče stiskanih kompozitov AZ91

Inspection of nickel-based boron carbide PTA coatings on AISI 4140 steel

Purpose Plasma transferred arc (PTA) coating is a novel method for surface-coating applications. In this method, the substrate is melted using a plasma arc, and surfacing agents such as carbides are introduced to the melt pool. The purpose of this study is to investigate the effect of boron carbide (B4C) in nickel-based coating on AISI 4140 steel. Design/methodology/approach Samples were tested on a ball-on-disc wear device, and the microstructure, as well as wear properties, were investigated using SEM and XRD. Findings The effect of B4C addition was shown to be linear, with a p-value of 0.0248, indicating strong evidence. The reason for this increase was found to be the increase in third-body generation resulting from hard phases that form couples with the soft base material, nickel. It was concluded that using 6 per cent B4C was the optimal solution. Originality/value In the literature, the effect of neither low temperature on a nickel coating with B4C nor B4C as a single surfacing agent in a nickel base has been investigated.

Processing and Characterization of Refractory Quaternary and Quinary High-Entropy Carbide Composite.

Quaternary high-entropy ceramic (HEC) composite was synthesized from HfC, Mo2C, TaC, and TiC in pulsed current processing. A high-entropy solid solution that contained all principal elements along with a minor amount of a Ta-rich phase was observed in the microstructure. The high entropy phase and Ta-rich phase displayed a face-centered cubic (FCC) crystal structure with similar lattice parameters, suggesting that TaC acted as a solvent carbide during phase evolution. The addition of B4C to the quaternary carbide system induced the formation of two high-entropy solid solutions with different elemental compositions. With the increase in the number of principal elements, on the addition of B4C, the crystal structure of the HEC phase transformed from FCC to a hexagonal structure. The study on the effect of starting particle sizes on the phase composition and properties of the HEC composites showed that reducing the size of solute carbide components HfC, Mo2C, and TiC could effectively promote the interdiffusion process, resulting in a higher fraction of a hexagonal structured HEC phase in the material. On the other hand, tuning the particle size of solvent carbide, TaC, showed a negligible effect on the composition of the final product. However, reducing the TaC size from −325 mesh down to <1 µm resulted in an improvement of the nanohardness of the HEC composite from 21 GPa to 23 GPa. These findings suggested the possibility of forming a high-entropy ceramic phase despite the vast difference in the precursor crystal structures, provided a clearer understanding of the phase transformation process which could be applied for the designing of HEC materials.

Processing, microstructure and mechanical properties of HfB2-ZrB2-SiC composites: Effect of B4C and carbon nanotube reinforcements

The fully dense HfB2-ZrB2-SiC composites were processed using spark plasma sintering (SPS) at 1850 °C. The effect of reinforcements (B4C and CNT) on the densification as well as mechanical properties were investigated and compared (with monolithic) in the present study. The study showed that the addition of B4C and CNT were not only beneficial for the densification but also towards enhancing the mechanical properties (hardness, elastic modulus, and fracture toughness) of HfB2-ZrB2-SiC composites. The augmentation in the mechanical properties establish the synergy between solid solution formation (with the equimolar composition of HfB2/ZrB2) and the reinforcements (SiC, B4C, and CNT). The highest increase in the indentation fracture toughness with the reinforcements of B4C as well as CNT is >3 times (~13.8 MPam0.5 when it is 3–4 MPam0.5 for monolithic ZrB2/HfB2) on HfB2-ZrB2-SiC composites, which is attributed to the crack deflection and pull-out mechanisms. An increase in the analytically quantified interfacial compressive residual stresses in the composites during SPS processing with the synergistic addition of reinforcements (SiC, B4C, and CNT) and its effect on the indentation fracture toughness has also been addressed.

Microstructural evolution and mechanical properties of in-situ as-cast beta titanium matrix composites

The aim of this research is to investigate the effects of B4C additions on microstructure refinement and mechanical properties, due to in-situ formation of TiB and TiC in a matrix of beta titanium by casting process. Researches have been done on the individual effects of TiC and TiB compounds in titanium composites, however, their hybrid effect has been scarcely explored in beta titanium alloys. The effects on lattice parameter were investigated by Rietveld refinement and EDS analysis. The beta lattice parameters increased due reaction between Ti and B4C. DTA analysis revealed the sequence of phase formation on heating and cooling around the melting point, being confirmed by investigation of orientation relationship between phases by EBSD and pole figure analysis. Orientation relationships are {312}TiB//{112}β, {112}TiC//{112}β for the smallest addition of B4C, {113}TiC//{112}β for the remaining composites, and {010}TiB//{011}TiC between the particles. Grain size reduced by half with 0.5% addition of B4C, while 3% addition made grains 25 times smaller than the alloy. Young's modulus and hardness increased with the addition of boron carbide. An analysis of the hardness of the materials was carried out from a nano to a macro scale. The as-cast composite materials have a refined structure with improved mechanical properties in comparison to the commercial alloy.

Beneficial effects of B4C addition on the microstructure and mechanical properties of SiC ceramic joints diffusion bonded with Ti3SiC2

The interfacial microstructure and mechanical properties of SiC ceramic joints diffusion bonded via spark plasma sintering with a powder mixture of Ti3SiC2 and B4C were investigated. The content of B4C ranging from 0 to 20 wt% was added into Ti3SiC2. Microstructure analysis results indicated that B4C in-situ reacted with Ti3SiC2 to form fine-sized TiB2, TiC, SiC, and carbon in the joint. The volume fraction of these reaction formed phases and coefficient of thermal expansion of the composite interlayer were calculated. The proper addition of B4C (5–15 wt%) was beneficial for the improvement of joint strength. The optimal amount of B4C addition was 7.5 wt%. The shear strength of the joint bonded with 7.5 wt% B4C addition reached 112.5 ± 8.3 MPa, which was 53.9% higher than that bonded without B4C addition. Vickers hardness of the composite interlayer was enhanced with the B4C addition. Toughening mechanisms including delamination and kinking of Ti3SiC2, crack deflection, crack bridging, and crack branching were observed in the composite interlayers.

Corrosion resistance of sintered SiC against fluorinated plasmas

α-SiC fabricated by the sintering method was developed as an alternative to the widely used β-SiC made by chemical vapor deposition for various functional components used in the plasma process chamber. By adapting the sintering method, larger and thicker SiC components can be fabricated practically compared with the chemical vapor deposition. Two sintering additives, Y2O3-Al2O3 and B4C, were used in the sintering processes, and the etching stability of sintered SiC against fluorinated plasmas, including SF6/Ar plasma and CF4/O2/Ar plasma, was investigated. For sintered SiC with Y2O3-Al2O3 additives, the etching rate was smaller than that of the chemical-vapor-deposited SiC, mainly because nonvolatile fluoride and/or oxides of Y and Al remained on the surface and served as a protective layer. For sintered SiC, the B4C additives, the etching rate, and the surface structure after plasma irradiation were similar to the case of the chemical-vapor-deposited SiC. The results suggest that the B4C additive has little effect on the etching stability, because fluorides of B and C are volatile, and no residue is formed, contrary to the case of the Y2O3-Al2O3 additives.

Effective Activation Energy for the Solid-State Sintering of Silicon Carbide Ceramics

Effective activation energy for densification of SiC in the presence of C and B4C additives is determined by constant heating rate experiments through analysis of shrinkage in hot pressing. The activation energy (AE) for sintering increased linearly with the relative density (RD) in two different regimes. The effective AE increased from 407 ± 50 kJ/mole at 75 pct RD to 1132 ± 75 kJ/mole at 95 pct RD. Lattice diffusion is proposed as the predominant mechanism for SiC densification at higher density. This is also validated by the uniform distribution of sintering additive through electron probe microanalysis. The low AE in the regime of lower density could be attributed to the pressure-assisted particle rearrangement during hot pressing. The relative contribution of both the mechanisms between two density limits resulted in the change in AE for sintering. The mechanisms of defect generation resulting in densification are also discussed.

Effects of B4C addition on the microstructure and properties of porous alumina ceramics fabricated by direct selective laser sintering

Direct selective laser sintering (dSLS) is a promising method for the fabrication of complex-shaped ceramic parts. In this paper, boron carbide (B4C) was used as an inorganic additive to improve the laser sintering behavior of alumina. The effects of B4C addition on the microstructure and mechanical properties of porous alumina ceramics were investigated. Mixture of alumina powders and different amount of B4C were directly sintered using different SLS parameters. Results indicated that the process window of alumina could be expanded by the addition of B4C. Furthermore, the amount of B4C played an important role in surface morphologies of alumina ceramics. It could be explained by the increase of mass transfer due to the addition of B4C, which enhanced the densification process. The compressive strength of sintered samples increased with the increase of B4C, which reached its maximum value when the content of B4C was 7 wt% and the density of the samples after post treatment could reach 1.4 g/cm3. In addition, a size expansion phenomenon was observed. The size expansion could reach 5% after SLS, which could be attributed to the pin effects and oxidation behavior of B4C particles.

Enhanced bending strength and thermal conductivity in diamond/Al composites with B4C coating

Diamond/Al composites containing B4C-coated and uncoated diamond particles were prepared by powder metallurgy. The microstructure, bending strength and thermal conductivity were characterized considering the B4C addition and diamond fraction. The influence of B4C coating and fraction of diamond on both bending strength and thermal conductivity were investigated. The bending strength increased with decreasing diamond fraction. Moreover, addition of B4C coating led to an obvious increase in bending strength. The peak value at 261.2 MPa was achieved in the composite with 30 vt.% B4C-coated diamond particles, which was about twice of that for 30 vt.% uncoated diamond/Al composite (140.1 MPa). The thermal conductivity enhanced with the increase in diamond fraction, and the highest value (352.7 W/m·K) was obtained in the composite with 50 vt.% B4C-coated diamond particles. Plating B4C on diamond gave rise to the enhancement in bending strength and thermal conductivity for diamond/Al composites, because of the improvement of the interfacial bonding between diamond and aluminum matrix.

Effect of bamboo char and boron carbide particles on mechanical characteristics of Aluminum 6061 hybrid composites

In present day Metal matrix composites(MMCs) are widely used in automotive and aeronautical domains due their superior mechanical properties compared to base metal. The current study evaluates the potentiality of conventionally prepared bamboo char particulates along with commercial grade B4C particulates as micro fillers dispersed into the Aluminium 6061 matrix. Three different compositions are fabricated through mechanical stir casting. Density measurements, tensile tests and Brinell hardness tests were carried out along with SEM fractographical analyses. It has been observed that addition of B4C and bamboo char led to an increase the hardness and tensile properties of aluminium 6061. But higher content of B4C caused a quasi-brittle mode of fracture.

Synergistic Effects of B4C and Sn on the Coupled Growth Pattern and Mechanical Properties of Mg–Y–Zn–Mn Alloy Containing LPSO and W Phases

The effect of boron carbide (B4C) particles and Sn on the microstructure and mechanical properties of Mg94Y2.5Zn2.5Mn1 alloy is mainly studied in this work. The results show that separated addition of B4C and Sn could not achieve very good results. The separated addition of Sn significantly promotes the formation of LPSO phase, but it cannot change the growth pattern of LPSO phase and W phase. Adding B4C changes the growth pattern of LPSO phase, but cannot effectively promote the formation of LPSO phase. The addition of B4C and Sn in combination achieves the growth pattern transformation of α‐Mg from irregular dendrite to equiaxed dendrite and refines the grain size, which makes LPSO phase and W phase no longer grow by coupled growth. When 0.02 wt% B4C and 0.35 wt% Sn is added, the Mg94Y2.5Zn2.5Mn1 alloy's growth pattern is changed and grains are refined, and thus exhibit superior mechanical properties. (Ultimate tensile strength of 255 MPa and elongation of 8.8%).

Study of Mechanical Properties and Drilling Behavior of Al7075 Reinforced with B4C

Metal grid composites (MMCs) have essentially moved forward properties including high specific strength, damping capacity, Specific modulus also great wear safety contrasted with unreinforced alloys, Aluminium 7075 need been chose as grid phase, concerning illustration constantly generally utilized by car and aviation requisition also hosting the most noteworthy quality around know business Al alloys. This contemplate investigates the mechanical also machinability properties of the aluminium 7075 fortified with boron carbide (B4C) with three aluminium reinforcements of 2%,4%,6% weight proportions from claiming B4C composites with need aid fabricated by Stir casting method. The composite tests were investigated should clarify those impact of diverse weight portions from claiming B4C support substance on the hardness, density, bending strength, ductile strength, also drilling properties of the coming about composites. Al7075 composite strengthened with 6wt. % B4C exhibited those most astounding hardness, flexural strength, density also prolongation “around those investigated examples. Aluminium grid make reinforced eventually reinforcing it for tough ceramic particles like SiC, Al2O3, and B4C and so on. This paper presents an overview of the effect of on B4C addition as reinforcement in Aluminium alloy,surface roughness test was carried on the basis of Taguchi’s L9orthogonal array taking three design factors such as material, speed and feed. Using Taguchi optimization method, optimum combination of these three factors was found 2% of B4C is good surface roughness result all among reinforcements. Surface roughness was analyzed on ANOVA (Analysis of Variance) and generates regression equation

B4C-MODIFIED SiO2-PHENOLIC COMPOSITES FOR ENHANCED ABLATION RESISTANCE

In the present paper, the silica-phenolic composite (S-Ph) composites with different amount of B4C were prepared, and the ablation tests of these composites were carried out using oxygen–acetylene jet. The ablation process was systematically investigated. The addition of B4C with appropriate amount can efficiently improve the ablation resistance of S-Ph. The results showed that S-Ph containing B4C powder of 2[Formula: see text]wt.% exhibited the lowest linear and mass ablation rate. The influence mechanism for the results was analyzed deeply. The surface morphologies, phase composition, density and thermal conductivity of composites were characterized using a scanning electron microscope (SEM), X-Ray Diffraction (XRD), Archimedes method, and thermal conductivity meter, respectively. The present investigation will provide a theoretical basis for the preparation of the ablation resistant material.

Microtopography and mechanical properties of vacuum hot pressing Al/B4C composites

Al/B4C composites with various volume contents of B4C (5%, 10%, 15%, 20%, and 25%) reinforcing the Al matrix, have been fabricated by vacuum hot press sintering at 680°C, with a soaking time of 90min and external pressure of 30MPa. Mechanical properties, phase composition, and microstructure of the Al/B4C composites are discussed to reveal the physical properties of the composites. Field emission transmission electron microscopy and selected area electron diffraction have been employed to verify the interior structure and crystal growth direction, respectively. The Vickers hardness, fracture strength, tensile strength, and maximum force attained the optimal values of 108.45 ± 4.02 HV, 585.70 ± 23.26MPa, 196.18 ± 2.48MPa, and 4.44 ± 0.17kN, respectively, for 25vol% B4C/Al composites. The static compression strength increased before the 15vol% B4C addition and then decreased, acquiring the highest value of 292.15 ± 2.09MPa for 15vol% B4C/Al composites. In general, the relative density and ductility of these composites consistently increased, with an increase in the volume content of Al, achieving a maximum of 99.22% and 54.63 ± 7.34%, respectively, for 5vol% B4C/Al composites.

Effects of in-situ formed TiB whiskers on microstructure and mechanical properties of spark plasma sintered Ti–B4C and Ti–TiB2 composites

Monolithic titanium, Ti–1 wt% B4C, Ti–2.5 wt% TiB2 were spark plasma sintered at 1050 oC for 5 min under 50 MPa. The effect of B4C and TiB2 additions on densification process, microstructural development and mechanical properties of titanium was investigated. The results revealed that relative density of undoped, B4C- and TiB2-doped Ti samples reached ~98-99%. X-ray diffraction patterns, thermodynamic assessments, and microstructural investigations verified the in-situ formation of TiB whiskers in both composite samples as well as appearance of TiC spheres in Ti–B4C composite. However, trace unreacted TiB2 and B4C additives were remained in the composites as a result of incomplete chemical reactions due to short-time SPS process. Compared to undoped Ti sample, grain growth was hindered when the sample was doped by B4C or TiB2. Elongation, ultimate tensile strength and Vickers hardness of B4C- or TiB2-doped samples were higher than those of monolithic titanium but bending strength of ceramic-doped samples significantly lower, compared to undoped titanium. These outcomes were discussed in detail and related to presence/formation of several ceramic phases with different morphologies in Ti matrix.

RETRACTED ARTICLE: Enhanced tensile strength and thermal conductivity in copper diamond composites with B4C coating

Boron carbide (B4C) coating on diamond particle is synthesized by heating diamond particles in a powder mix of H3BO3 and B in Ar atmosphere. The composition, bond state and coverage fraction of boron carbide coating on diamond particles are investigated. The boron carbide coating favors to grow on diamond (100) surface rather than on diamond (111) surface. Cu matrix composites reinforced with B4C-coated diamond particles were made by powder metallurgy. The addition of B4C coating gave rise to a dense composite. The influence of B4C coating on both tensile strength and thermal conductivity of the composite were investigated. When the B4C fully covered on diamond particles, the composite exhibited a greatly increase in tensile strength (115 MPa) which was much higher than that for uncoated-diamond/Cu (60 MPa) composites. Meanwhile, a high thermal conductivity of 687 W/mK was achieved in the B4C-coated-diamond/Cu composites.