B4C Particle Size Research Articles

Effects of particle size and content of cladding powder on in situ synthesized WC‐reinforced Ni‐based cladding layers

AbstractLaser cladding technology can obtain a cladding layer with good metallurgical bonding with the substrate and excellent performance. In situ growth of hard phase can effectively solve the problem of uneven distribution of reinforcements directly doped with hard particles. In this paper, 45# steel was adopted as the matrix material, WO3, B4C, Al, and Ni60 powder were used to prepare laser cladding and in situ synthesized WC (Tungsten Carbide) hard phase reinforced Ni‐based cladding layers. The effects of different laser cladding parameters, powder particle size, hard phase content on the microstructures and electrochemical properties of in situ synthesized WC hard phase reinforced Ni‐based cladding layer were analyzed. The results revealed that when the (WO3 + B4C + Al) mixed powder content was 25%, the bulk particles of WC phase in the cladding layer were most uniformly distributed in the cladding layer, which enhances the mechanical properties of the cladding layer. When the B4C particle size was 5 μm, the microhardness of the cladding layer was significantly higher than other cladding layers, and the enhancement mechanism of hardness by B4C is due to the Orowan strengthening caused by too small particle size of B4C.

Effect of B4C particle size and TiB2 content on the mechanical properties of B4C composites and their dynamic mechanical properties

AbstractB4C–MAS and B4C–TiB2–MAS ceramic composites were prepared by hot pressed sintering. The effects of particle size of B4C and TiB2 content on the microstructure and general mechanical properties of the ceramic composites were investigated by using X‐ray diffractometer, scanning electron microscope, and universal testing machine. The strengthening and toughening mechanism of ceramic composites is mainly attributed to the addition of magnesium–aluminosilicate (MAS) and thermal mismatch effect of TiB2. When the TiB2 content was 20 wt.%, the bending strength, fracture toughness, and Vickers hardness of B4C–TiB2–MAS ceramic composites were 375 MPa, 4.42 MPa·m1/2, and 23.9 GPa, respectively, and its relative density could reach 99.7%. The dynamic mechanical properties of B4C–TiB2–MAS ceramic composites were investigated at strain rates of 2000–6000 s−1 using a Separate Hopkinson Pressure Bar (SHPB) device. The results showed that the B4C–TiB2–MAS ceramic composites exhibited significant strain rate sensitivity. The dynamic compressive strength of the ceramic composites increased from 4634 to 5734 MPa with increasing strain rate in the tested strain rate range.

Influence of B4C Particle Size on the Microstructure and Mechanical Properties of B4C/Al Composites Fabricated by Pressureless Infiltration

To investigate the effect of B4C particle size on the microstructure and mechanical properties of B4C/Al composites, and to provide theoretical guidance for the subsequent thermal processing of composites, B4C/Al composites with varying B4C particle sizes (0.2 µm, 0.5 µm, 1 µm, 10 µm) were fabricated using pressureless infiltration. The microstructure of the composites was characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), while the mechanical properties were analyzed by hardness test, three-point bending and high temperature compression. The results indicated that Al3BC and AlB2 were the primary interfacial reaction products in B4C/Al composites, and interface reaction could be alleviated with increasing particle size. B4C/Al composites with larger B4C particle sizes exhibited a relatively uniform and discrete distribution of B4C, while those with smaller B4C particle sizes showed agglomeration of B4C. The Vickers hardness and peak flow stress of B4C/Al composites gradually decreased with the increase of B4C particle size, while the bending strength, flexural modulus, and fracture toughness tended to increase. In addition, when B4C particle size was 10 µm, the composites displayed optimal comprehensive performance with the lowest peak flow stress (150 MPa) and the highest fracture toughness (12.75 MPa·m1/2).

Effects of B4C particle size and content on microstructure and properties of in-situ TiB2-TiC composite coatings prepared by plasma spraying

In order to improve the surface properties of titanium alloy, in-situ TiB2-TiC composite coatings were successfully prepared by plasma spraying Ti-B4C composite powder. The effects of particle size and content of B4C raw powders on the phase composition, microstructure, and mechanical properties of the TiB2-TiC coatings were systematically evaluated. The results reveal that the decrease of B4C particle size had a significant effect on the increase of hard phases (TiB2 and TiC) in the 3Ti-B4C (1 μm) composite coating. Meanwhile, the density of the 3Ti-B4C (1 μm) coating was increased with the decrease of B4C particle size, so the microhardness of the 3Ti-B4C (1 μm) coating was significantly better than that of the 3Ti-B4C (19 μm) coating. The reduction of B4C (1 μm) content (Ti:B4C = 5: 1, 7: 1 and 9: 1) in the composite powders could promote the reaction of the system to form new phase TiB, and the main phases of the 5Ti-B4C, 7Ti-B4C and 9Ti-B4C coatings was finally transformed into TiC, TiB2 and TiB. The hardness of the composite coatings was improved with increasing of Ti: B4C from 3: 1 to 5: 1, but the hardness of the samples obtained by spraying 7Ti: B4C and 9Ti: B4C composite powders were drastically decreased. What's more, the 5Ti-B4C (1 μm) composite coating possessed good toughness. The toughening mechanism was mainly attributed to the grain refinement, dispersion strengthening and microstructure densification.

Influence of B4C particle size on the mechanical behavior of A356 aluminium composites

Influence of B4C particle size on the mechanical behavior of A356 aluminium composites

Reaction Behavior and Formation Mechanism of ZrB2 and ZrC from the Ni-Zr-B4C System during Self-Propagating High-Temperature Synthesis

Self-propagating high-temperature synthesis (SHS) is a good way to prepare ZrB2-ZrC/metal cermet composites. In this work, ZrB2-ZrC/Ni cermet composites with various Ni contents were successfully fabricated by SHS using the Ni-Zr-B4C system. The effects of Ni content and particle size of the B4C powder on the SHS reaction were investigated. The results indicated that with an increase in Ni content, the adiabatic temperature, maximum combustion temperature, ignition delay time, and ceramic particle size in the product all showed a gradually decreasing trend. The SHS products and the ignition of the SHS reactions were significantly dependent on the B4C particle size. The formation mechanism of ZrB2 and ZrC during SHS from the Ni-Zr-B4C system was proposed based on the combustion wave quenching experiment.

Probe-less friction stir spot processing (PFSSP) of AA5754/AA5083 joint by adding the B4C ceramics: Effect of shoulder features on mechanical properties and tribological behavior

This study aims to improve the local shear behaviors of dissimilar spot welds of Al alloys through a particle-dispersion strengthening mechanism. Probe-less friction stir spot processing of the AA5083-H112 and AA5754-O alloys with B4C ceramic reinforcement was investigated by modifying the tool shoulder surfaces. The smooth and scrolled shoulder tools were utilized for this study. The mechanical properties of the B4C-reinforced spots were examined via the use of the miniaturized shear punch testing method and the tensile-shear test. At an unchanged process condition, the scrolled shoulder tool improved particle dispersion and dislocation density to an extent while it significantly reduced the average B4C particle size from 60 to 6.71 μm more than that of the smooth shoulder tool. The scroll-pattern-assisted straining, material flow. The wear rate was significantly reduced in the sample fabricated with the scroll tool. The scrolled shoulder tool is recommended for the fabrication of the B4C-reinforced spots.

Influences of B4C content and particle size on the mechanical properties of hot pressed TiB2–B4C composites

ABSTRACT TiB2 ceramic has attracted many attentions due to its excellent performances both on mechanical and functional properties. However, it is still very difficult to obtain TiB2 bulks with full densification. Herein, TiB2–B4C composites were prepared via hot pressing at 1900°C under the pressure of 35 MPa with TiB2 and B4C as the raw materials. The influences of B4C content (0, 10 vol%, 20 vol% and 30 vol%) and particle size (0.50 µm, 3.12 µm and 7.09 µm) on the phase composition, relative density, microstructure and mechanical properties of TiB2–B4C composites were investigated. The using of 0.50 µm B4C brought more B2O3 which induced oriented growth of TiB2 grains and coarsened the obtained composites. When the raw B4C powders were 3.12 µm and 7.09 µm, the obtained composites with 20–30 vol% B4C could be fully densified. TiB2–30 vol% B4C composite prepared from 3.12 µm B4C powder resulted in the optimal mechanical properties. The bending strength, Vickers hardness, fracture toughness were 671 MPa, 27.93 GPa, and 3.91 MPa·m1/2, respectively. The excellent performance was attributed to its fine and homogenous microstructure.

Influence of B4C particle size on microstructure and damping capacities of (B4C+Ti)/Mg composites

Influence of B4C particle size on microstructure and damping capacities of (B4C+Ti)/Mg composites

Sol-Gel synthesis and characterization of SiC–B4C nano powder

In the present research, SiC–B4C nano powders were synthesized through sol–gel process in water–solvent–catalyst–dispersant system. In order to evaluate the formation mechanism of the product during sol-gel process, TEM, SEM, DTA/TG, BET, XRD, FTIR and DLS analysis methods were employed. The nanometric size of precursor was controlled by dispersing agents and controlling pH inside the sol. DLS analysis revealed that the particles of the precursor inside the sol were below 10 nm. FTIR results indicated that the (Si–O–B) bonds were formed in the dried gel powder, due to hydrolysis and condensation reactions. DTA analysis confirmed that the synthesis temperature was lower than 1400 °C. XRD results implied the presence of cubic β-SiC and the rhombohedral B4C phases, which were formed simultaneously in the SiC–B4C nanopowder. BET analysis indicated a high surface area for the particles of about 171.42 m2/g, and that the surfaces of these particles were meso porous. SEM analysis exhibited that SiC– B4C particle size was in the range of 20–40 nm with homogenous morphology. Ultimately, the TEM/EDS microstructural analysis showed that B4C and SiC particles were formed simultaneously and uniformly in the final product.

Combustion of B4C/KNO3 binary pyrotechnic system

Presented herein is an experimental study on the combustion of B4C/KNO3 binary pyrotechnic system. Combustion products were tested using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS). According to the results of tests and CEA calculation, the combustion reaction equation was established. The flames and burning rates were recorded by a high speed camera and a spectrophotometer. The effect of B4C particle size on the thermal sensitivity of B4C/KNO3 was investigated by differential scanning calorimetry (DSC) techniques. In addition, a reliable method for calculating the flame temperature was proposed. Based on the results of experiments, the combustion reaction mechanism was briefly analyzed. The burning rate, flame temperature and thermal sensitivity of B4C/KNO3 increase with the decrease of B4C particle size. The mass ratio of B4C/KNO3 has a great effect on combustion properties. Oxidizer-rich compositions have low flame temperatures, low burning rates, and provide green light emission. The combustion reactions of fuel-rich compositions are vigorous, and the B4C/KNO3 with mass ratio of 25:75 has the highest burning rate and the highest flame temperature.

Effect of amount of TiB2 and B4C particles on tribological behavior of Al7075/B4C/TiB2 mono and hybrid surface composites produced by friction stir processing

In this study, by friction stir processing, we fabricated several defect-free Al7075/B4C/TiB2 mono and hybrid surface composites containing various amounts of B4C and TiB2 reinforcements with high quality interfacial bonding with substrate, fine recrystallized matrix grains, and homogenous dispersion of ceramic particles through the matrix. The composite region of hybrid composite samples was more constricted compared with that of mono composite samples. All hybrid composites had more hardness and wear resistance in comparison to Al/B4C mono composite sample. Among different hybrid composites, the most optimal dispersion of ceramic particles, minimum size of B4C and TiB2 ceramic particles, the lowest friction coefficient, and the highest hardness and wear resistance belonged to the hybrid composite containing equal weight percentage of B4C and TiB2 ceramic particles (named 50%B4C-50%TiB2 hybrid composite). The hardness and wear resistance of the Al7075/B4C, Al7075/TiB2 mono composites and the 50%B4C-50%TiB2 hybrid composite were respectively enhanced by (91%, 121%, 107%) and (67%, 82%, 87%) regarding Al7075 base alloy. During wear, an unstable-simple tribolayer was formed on the surfaces of Al7075 base alloy and unreinforced FSPed samples; however, a more stable mechanically mixed tribolayer containing a mixture of oxygen, ceramic particles, and alloying elements of Al7075 base alloy and steel counterface was formed on the surface of the composite samples. The most stable tribolayer with the highest self-lubricating behavior belonged to the 50%B4C-50%TiB2 hybrid composite owing to the high amount of iron and very low amount of B4C in the tribolayer, resisting the subsurface of tribolayer to crack propagation.

Effect of B4C Particle Size on the Properties of Al/(Al–B4C)/Al Functionally Gradient Material

The functionally gradient material (FGM), consisting of pure Al outer layer and Al–B4C inner layer, was fabricated by semi-continuous casting with subsequent hot rolling. B4C particles of four different sizes (11, 26, 53, and 75 μm) were used as the reinforcement phase. The effect of B4C size on the microstructure and mechanical properties of the FGM composites was analyzed. Obtained results show that the B4C particles are uniformly distributed in the inner layer. With the increase of B4C particle size, the Brinell hardness of these FGMs increases, but the impact properties decrease.

Impact of Particle Size Distribution for Variable Mixing Time on Mechanical Properties and Microstructural Evaluation of Al-Cu/B4C Composite

Abstract In the present work the combined effects of particle size and distribution on the mechanical properties of the 20vol.% B4C particle reinforced Al–Cu alloy composites by powder metallurgy is investigated. The aim of this work was to evaluate the effect of mixing time (5h, 15h and 25h) and particle size (23µm and 67µm) of B4C particles on the metallurgical and mechanical properties. It has been found that small ratio between matrix/reinforcement particles sizes resulted in more uniform distribution in the matrix. The particles distributed more uniformly in the matrix with increasing in mixing time. The results also showed that homogenous distribution of the B4C particles resulted in higher hardness, ultimate tensile strength, yield strength and elongation. Fracture surface observations showed that the dominant fracture mechanism of the composites with small B4C particle size (23µm) is ductile fracture of the matrix, accompanied by the “pull-out” of the particles from the matrix, which is attributed to positive effect of reinforcement particles in resistance to the movement of dislocations while the dominant fracture mechanism of the composites with large B4C particle size (67µm) is ductile fracture of the matrix, accompanied by the B4C particle fracture

Fatigue and Compression Characteristics of Al 6061–B4c Composite Materials

Aluminum matrix composites reinforced with boron carbide are a kind of materials that are widely used because of high strength, low density, and improved tribological properties. In this study, mechanical properties of Al 6061–B4C composites reinforced with B4C of three different particle sizes were investigated. In the Al 6061–B4C composite materials, produced by the powder metallurgy methods (extrusion of billets obtained by sintering at temperature of 550°C under pressure of 450 MPa), the change of mechanical properties such as hardness, compressive strength, and fatigue life, related to B4C particle size and the applied heat treatment mode (aging at 180°C for 5 h), were investigated. The hardness of the materials is increased with B4C grain size and the heat treatment. After the heat treatment, the fatigue life of Al 6061–B4C (3 μm) material increases slightly, while that of the composite materials decreases with larger size of B4C reinforcement. The fatigue life of the composite materials reinforced with a larger grain size B4C is reduced by heat treatment. While the compression test data of untreated composite materials were similar to each other, the heat treatment increased these values in all samples. The highest increase in the compression strength was observed in the composite reinforced with 17 μm sized B4C. The addition of graphite reduces the deformation ability of the composites.

The effect of particle size on microstructure, relative density and indentation load of Mg-B4C composites fabricated at different loading rates

The effect of reinforcing particle size on microstructure, relative density and indentation of Mg reinforced by 0, 1.5, 3, 5 and 10% volume fractions of nano- and micro-sized B4C was investigated. The composites were fabricated through powder compaction technique at strain rates of 1.6 × 103 s−1, 8 × 102 s−1 and 8×103 s−1 using split Hopkinson bar, drop hammer and Instron, respectively. The results indicated that the size of B4C and loading rate had significant effect on relative density. For example, the relative density of Mg-10 vol.% B4C nanocomposite was around 2.5% higher than that of its corresponding microcomposites. The relative density of the samples produced at high rate of loading was in average 1.2% higher than that of the samples fabricated quasi-statically. The results of indentation tests on the produced nanocomposite and microcomposite samples also revealed that loading rate and B4C particle size had significant effect on strength of specimens. For example, for Mg-5 vol.% B4C, the maximum load in load–depth curve of the specimens produced by split Hopkinson bar increased from 530 N for micron-sized B4C to 780 N for nano-sized B4C, around 45% improvement. Moreover, nanocomposites had better indentation resistance compared to similar micro composites fabricated using the three methods.

Effects of particle size of raw materials on the characteristics of TiB2–SiC composites fabricated from B4C, TiC and Si powders

We studied the effects of particle size of raw materials (B4C, TiC and Si powders) on the characteristics of both TiB2–SiC composite powders and ceramics. Results show that the size of B4C and Si particles hardly affects the size of TiB2 and SiC particles because B4C is decomposed and consumed during the formation of TiB2, and Si is melted during the formation of SiC. The size of SiC particles is within the nano and submicron scale. However, the size of TiC particles determines the sizes of TiB2 particles and TiB2 grains in the composite ceramics because TiC particles serve as templates to form TiB2 particles. Consequently, the microstructure and mechanical properties of the TiB2–SiC composite ceramics are affected. The TiB2–SiC composites fabricated using nano-sized TiC powder possess smaller grain size, better dispersibility and more reasonable crack propagation path, thereby obtaining the optimal mechanical properties (Vickers hardness of 30.2 GPa, flexural strength of 732 MPa and fracture toughness of 7.37 MPa m1/2).

Effects of B4C particle size on the microstructures and mechanical properties of hot-pressed B4C–TiB2 composites

Full dense B4C–30 vol% TiB2 composites were prepared by hot pressing at 2000 °C under 35 MPa from four different starting B4C powders with their medium particle sizes ranging from 0.5 to 35.8 µm. The effects of B4C particle size on the microstructures and mechanical properties of composites were investigated. The results indicated that both B4C and TiB2 grains grew during sintering process, and each kind of grains had a pinning effect on the grain growth of the other. With coarse B4C powders as raw materials, TiB2 grains in obtained B4C–TiB2 composites tended to grow with the [001] zone axis parallel to the applied pressure direction, which possibly reinforced the composites. When the particle size of the starting B4C powder was 7.09 µm, the obtained B4C–TiB2 composite exhibited the optimized mechanical properties including a flexural strength of 754 MPa, a Vicker hardness of 30.01 GPa and a fracture toughness of 5.23 MPa m1/2, respectively, due to the most homogenous and finest microstructures.

Effect of B4C particle size on the mechanical properties of B4C reinforced aluminum matrix layered composite

Abstract Reinforcement particle size is very important for the performance of metal ceramic composites. This work studied the influence of B4C particle size on the mechanical properties of Al matrix layered composites. These composites were fabricated using a simplified semicontinuous casting and hot-rolling process. To obtain an optimized filling structure of particles, Horsfield filling principle was applied to determine the size and mass fraction of B4C particles. Four sizes of B4C particles were used with various combinations. The results showed that with the increase of the B4C particle size and fine B4C mass fraction, the hardness of the composites decreases whereas the impact strength and ultimate tensile strength increase. The residual stress at interface should be responsible for the variation in properties. Besides, the interparticle distance also contributes to the change in impact strength and ultimate tensile strength.

Wear behavior of B4C reinforced AZ91 matrix composite fabricated by FSP

In the present study AZ91 matrix composite with B4C reinforcement was fabricated by friction stir processing (FSP). In addition to grain refinement of AZ91, the B4C particles resulted in improved wear resistance and microhardness. Study comprises of composite fabrication by FSP under natural cooling. The specimens were characterized by Optical Microscopy and Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS). Wear, the tribological property, was studied on pin-on-disc apparatus and results have confirmed the property enhancement. The wear test has been carried out at 1m/s sliding velocity at 5N normal load for FSPed and as cast specimens at sliding distance of 2000m. Further analysis has revealed that microhardness and wear resistance improve as the B4C particle size was increased from sub microns to 50µm.