Effect Of B4C Addition Research Articles

Construction of three-dimensional network morphology titanium matrix composites via adding nano B4C: As-built and heat-treated scenarios

This study examines the role of nano B4C addition in improving the mechanical properties of Ti–6Al–4V (Ti64) alloys fabricated by laser melting deposition under as-built and heat-treated conditions. However, the enrichment of reinforcing phases generated by in situ production at grain boundaries causes a serious reduction in ductility, limiting the development of high-performance titanium matrix composites. To avoid this deficiency, the fabricated titanium matrix composites (TMCs) were subjected to three different heat treatment programmers, namely, subtransus heat treatment, supertransus heat treatment and triple heat treatment. The effects of B4C addition and heat treatment on microstructure, texture and mechanical properties were systematically investigated. The results show that TiB and TiC, synthesized in situ, promote the precipitation of α-Ti with a non-Burgess orientation relationship, and weakening the texture intensity of α-Ti. The ultimate tensile strength of the in situ synthesized (TiB + TiC) reinforced Ti64 composites is 1168 MPa, which is 35.5 % higher than the ultimate tensile strength of the Ti64 alloys. However, this effect resulted in a decrease in elongation at break to 2.5 %. An excellent combination of strength and fracture strain of 1060 MPa and 9.3 %, respectively, was simultaneously achieved for the heat-treated TMCs. The excellent ductility is mainly attributed to the microstructure consisting of primary equiaxed-α, ultrafine αs lamellar and retained β phase has been obtained after triple heat treatment. This finding offers significant guidance for the additive manufacturing of TMCs microstructures in order to attain the desired mechanical properties.

On the effects of B4C addition on the microstructure, mechanical properties, wear and thermal stability of TiCN- Co -Cr3C2-Si3N4 cermets developed by vacuum hot pressing

This paper reports the development of TiCN - Co - Cr3C2 - Si3N4 cermets modified with the addition of B4C. Cermets of three different compositions with varying B4C in TiCN - Co - Cr3C2 - Si3N4 were fabricated. The TiCN, Co, Cr3C2, Si3N4 and B4C powders in the combinations 80%TiCN-5%Co-5%Cr3C2–5%Si3N4–5%B4C; 75%TiCN-5%Co-5%Cr3C2–5%Si3N4–10%B4C; 70%TiCN-5%Co-5%Cr3C2–5%Si3N4–15%B4C were ground in a ball milling unit for six hours at a speed of 300 rpm at a ball-to-powder ratio of 10:1. The powders were then sintered in a vacuum hot press at a temperature of 1600 °C and a pressure of 50 MPa with soaking time of 90 min. For comparison purpose, 90%TiCN-5%Co-5%Cr3C2 cermet was prepared. The microstructure of the sintered cermets revealed the core-rim structure. The Vickers hardness test was done with a load of 10 Kg and for duration of 10 s. Fracture toughness was measured using the crack length data obtained from the hardness test using scanning electron microscopy. The cermet with a composition 75% TiCN-5%Co-5% Cr3C2–5% Si3N4–10% B4C produced higher hardness of 26.53 ± 0.56 GPa and fracture toughness of 10.29 ± 0.18 MPam and 70% TiCN-5%Co-5% Cr3C2–5% Si3N4–15% B4C showed high fracture toughness value of 11.23 ± 0.09 MPam with hardness value of 21.05 ± 0.10 GPa. The cermet composition 75% TiCN-5%Co-5% Cr3C2–5% Si3N4–10% B4C retained the hardness of 16.85 GPa even after annealing at 600 °C. The sintered cermets tend to form TiO2 which determines the hardness of the annealed cermets at a range of 600 °C – 1000 °C. The presence of these oxides tends to decrease the hardness. The wear test was performed taking the cermet as the pin material. The abrasive and adhesive wear mechanisms were dominant in the cermets. The harder precipitates formed tend to increase wear resistance by reducing the wear rate. The harder precipitates (TiN and TiB2) formed mainly due to the addition of Si3N4 and B4C, this addition promotes adhesive wear by a tribolayer formation.

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

Effect of B4C Addition on Microstructure and Wear Resistance of Laser Cladding NiCrBSi Coatings

Effect of B4C Addition on Microstructure and Wear Resistance of Laser Cladding NiCrBSi Coatings

The tensile creep behavior of a B4C-bearing high Nb containing TiAl alloy

In the present paper, the effect of B4C addition on elevated temperature tensile properties and creep resistance of as-cast Ti–43Al–6Nb–1Mo–1Cr alloy has been characterized. Experimental results reveal that 0.2 at. % B4C can improve the ultimate tensile strength and elongation of alloy at 800 °C. The steady-state creep rate of alloy with the addition of B4C decreases from 2.3 × 10−6 s−1 to 5.2 × 10−7 s−1 at 800 °C under 300 MPa. The stress exponent (n) and the apparent activation energy (QC) of alloy with the addition of B4C are measured to be 3.18 at 800 °C and 416.410 kJ/mol under 300 MPa, respectively. Combining microstructure observation, the dominant creep deformation mechanisms of Ti–43Al–6Nb–1Mo–1Cr-0.2B4C alloy at 800 °C under 300 MPa are mechanical twinning and dislocation slipping pinned by solute carbon atoms. During creep, the α2 lamellar dissolution and α2/γ interface migration occur simultaneously, and the dynamic recrystallization at colony boundary effectively alleviates the stress concentration resulting from dislocation pile-ups. In addition, the initiation of cavities as well as the propagation and coalescence of cracks are the main creep fracture features. Particularly, TiB can prevent dislocation motion and prolong the crack propagation path to increase creep resistance.

Effect of B4C addition on the solidus and liquidus temperatures, density and surface tension of type 316 austenitic stainless steel in the liquid state

• Solidus and liquidus temperatures of type 316 austenitic stainless steel − B 4 C system. • Density of molten type 316 austenitic stainless steel − B 4 C system. • Surface tension of molten type 316 austenitic stainless steel − B 4 C system. • Non-contact high-temperature thermophysical-property measurement technique. The effects of B 4 C addition on the solidus and liquidus temperatures of type 316 austenitic stainless steel (SS), and on the density and surface tension of molten SS, were experimentally studied. The solidus temperature of SS− x mass% B 4 C (0 ≤ x ≤ 10) monotonically decreased from 1666 to 1307 K with B 4 C addition. The liquidus temperature had a minimum at around 2.5 mass% B 4 C, and increased with further B 4 C addition up to 10 mass%. The density and surface tension of molten SS− x mass%B 4 C were successfully measured over a wide temperature range (including an undercooling region) via an electromagnetic-levitation technique. The density of each sample decreased linearly with temperature. The density also monotonically decreased with B 4 C content. Although the addition of B 4 C had no clear effect on the surface tension of SS− x mass%B 4 C, sulfur dissolved in SS316L caused a significant decrease in the surface tension.

Effect of B4C reinforcement on microstructure, residual stress, toughening and scratch resistance of (Hf, Zr)B2 ceramics

Effect of B4C addition on the lower damage tolerance of spark plasma sintered (Hf, Zr)B2 based ceramics has been elucidated. Increased densification (from 89% to 95%) with B4C addition has elicited hardness and elastic modulus increase from 25 GPa to 38 GPa (52%) and 439 GPa–635 GPa (45%), respectively. Systematic 3–9 vol% B4C addition resulted in an increased fracture toughness (from 2.2 MPa m0.5– 4.4 MPa m0.5) and flexural strength (from 320 MPa to 357 MPa) compared to that of (Hf, Zr)B2 due to synergistic effect of solid solutioning and compressive residual stresses generated around reinforcement. The decreased wear rate (from 0.163 mm3/N.m to 0.061 mm3/N.m) with optimal B4C addition, affirms enhanced damage tolerance of (Hf, Zr)B2 composite. Enhanced cracking and fracture in (Hf, Zr)B2 shifts to abrasion induced restricted micro-cracking as micro-scratch wear mechanism with B4C addition. Estimated elastic-modulus and extracted scratch-hardness are correlated with microstructural attributes of porosity, phase content and residual stress in (Hf, Zr)B2 composites.

Effect of B4C addition on the oxidation behavior of borosilicate glass repairing coating for C/C brake materials

The thermal properties of the borosilicate glass repair coating with B4C as a ceramic additive were analyzed, and the changes of thermal expansion, density, and porosity of the glass materials were investigated to characterize the physical characteristics of the repair coating. The results showed that this repair coating displayed variable oxidation resistance and self-healing property at temperatures from 700 to 900 °C, depending on the B4C content. The B2O3 generated from B4C can be dissolved into the borosilicate glass, which could significantly change the coefficient of thermal expansion and the softening temperature of the glass. When B4C content was 25 wt%, the coating with the lowest porosity and oxygen permeability was formed. A model of structure transition of the oxidation-resistant mechanism of the B4C added borosilicate glass coating was discussed.

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

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.

Effects of B4C Addition on the Microstructure and Magnetic Properties of FePt-C Granular Thin Films for Perpendicular Magnetic Recording

Effects of B4C addition on the microstructure and magnetic properties of FePt and FePt-C thin films have been studied. A high coercivity of 2.11 T with good squareness is achieved by B4C addition. By analyzing the mechanism and different isolation effects of B4C and C as segregants, a double-layer approach has been developed and a coercivity of 1.96 T is achieved with column-like FePt grains. The grain size and the size distribution are not deteriorated substantially compared with the single-layer case. These results indicate that addition of B4C as segregant is beneficial for the modification of microstructure and magnetic properties.

Effect of B4C on the properties and microstructure of Al2O3 -SiC-C based trough castable refractories

The effect of B4C addition (0.5wt%, 1wt%, 1.5wt%, 2wt%) on properties and microstructure of Al2O3-SiC-C (ASC) based trough castables was studied in this paper. The results showed that the bulk density of samples after firing at 1450°C decreased when the addition of B4C was over 1wt%. The cold modulus of rupture of samples improved significantly with the addition of B4C when the treating temperature was over 1100°C. Among them, sample with 1.5wt% of B4C had the best anti-slag performance and thermal shock resistance. The SiC fibers were formed in the non-oxidized zone of ASC castables with addition of B4C after firing at 1450°C in air condition. The obtained fibers rooted in the walls of inner micropores of samples with the diameter of 50–200nm, and the lengths of 10–50µm. The experiment revealed the nucleation of SiC started at about 1000°C, and then the growth of SiC fibers happened at higher temperature in a favorable condition. A stepped twin structure perpendicular to the growth direction of fibers could be observed. Finally, the growth mechanism was interpreted by thermodynamic calculations.

Investigation of TaC–TaB2 ceramic composites

The TaC–TaB2 composition was sintered by spark plasma (SPS) at 1900–2100°C and applied pressure of 30 MPa. TaC and 2–3 wt% B4C were used as starting powders. Densification process, phase evolution, microstructure and the mechanical properties of the composites were investigated. The results indicated that the TaC–TaB2 composition could be SPS to 97% of theoretical density in 10 min at 2100°C. Addition of B4C leads to an increase in the density sample from 76 to 97%. B4C nano-powder resists grain growth even at high temperature 2100°C. The formation of TaB2/carbon at TaC grain boundaries helps in pinning the grain boundary and inhibiting grain growth. The phase formation was associated with carbon and boron diffusion from the starting particles B4C to form TaB2 phases. TaC grain sizes decreased with increase in B4C concentration. Samples with 2.0 wt% B4C composition had highest flexure strength up to 520 MPa. The effect of B4C addition on hardness measured by microhardness has been studied. Hardness of samples containing 3.0 wt% B4C was 16.99 GPa.

Brazing SiC ceramic using novel B4C reinforced Ag–Cu–Ti composite filler

The development of new composite fillers is crucial for joining ceramics or ceramics to metals because the composite fillers exhibit more advantages than traditional brazing filler metal. In this research, novel B4C reinforced Ag–Cu–Ti composite filler was developed to braze SiC ceramics. The interfacial microstructure of the joints was characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The effect of B4C addition and brazing temperature on the microstructure evolution and mechanical properties of the joints was analyzed. The results revealed that TiB whisker and TiC particles were simultaneously synthesized in the Ag-based solid solution and Cu-based solid solution due to the addition of B4C particles. As the brazing temperature increased, the thickness of Ti3SiC2+Ti5Si3 layers adjacent to SiC ceramic increased. Desirable microstructure similar to the metal matrix reinforced by TiB whisker and TiC particles could be obtained at brazing temperature of 950°C. The maximum bending strength of 140MPa was reached when the joints brazed at 950°C for 10min, which was 48MPa (~52%) higher than that of the joints brazed using Ag–Cu–Ti filler.

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.

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

Spark plasma sintered tantalum carbide: Effect of pressure and nano-boron carbide addition on microstructure and mechanical properties

TaC and TaC–1wt.% B4C powders were consolidated using spark plasma sintering (SPS) at 1850°C and varying pressure of 100, 255 and 363MPa. The effect of pressure on the densification and grain size is evaluated. The role of nano-sized B4C as sintering aid and grain growth inhibitor is studied by means of XRD, SEM and high resolution TEM. Fully dense TaC samples were produced at a pressure of 255MPa and higher at 1850°C. The increasing pressure also resulted in an increase in TaC grain size. Addition of B4C leads to an increase in the density of 100MPa sample from 89% to 97%. B4C nano-powder resists grain growth even at high pressure of 363MPa. The formation of TaB2/Carbon at TaC grain boundaries helps in pinning the grain boundary and inhibiting grain growth. The effect of B4C addition on hardness and elastic modulus measured by nanoindentation and the indentation fracture toughness has been studied. Relative fracture toughness increased by up to 93% on B4C addition.

Pressureless sintering of ZrB 2–SiC ceramics: the effect of B 4C content

Systematic studies were carried out on the sintering of ZrB2–SiC ceramics without any external pressure being applied. The densities, mechanical properties and microstructures with different contents of B4C were investigated. The results showed that B4C additions were beneficial not only for the sintering process but also for the oxidation resistance. The sintered ZrB2–SiC ceramics with 0.4 wt.% B4C addition had an average strength of 382 ± 24 MPa and a modulus of 405 ± 34 GPa. The hardness and toughness were 13.4 ± 0.4 GPa and 3.7 ± 0.2 MPa m1/2, respectively. The effect of B4C addition on the oxidation resistance of ZrB2–SiC was studied by observing the mass changes and the residual strengths of samples after oxidized treatments.