B4C Surface Research Articles

Effect of surface micro-texture morphology on the wettability of aluminum alloy on B4C surface

Abstract To enhance the wettability of AlSi10Mg on the B4C surface, a 2D laminar two-phase flow, phase-field coupled multi-field model is utilized to investigate the effect of surface micro-texture morphology on the wettability of AlSi10Mg on B4C surfaces and optimize the morphology of the micro-texture with the best improvement of the interfacial wetting effect. The results of the study show that compared to the square texture, the conical texture has a better effect on the improvement of the wettability of the interface. The best wettability of AlSi10Mg on the B4C surface was obtained at a 1:1 depth-to-width ratio of the conical texture, and the contact angle of the Al droplet is 47.9, which is improved by 21.22% compared to that of the smooth interface. The interfacial wetting state is transformed from the Wenzel state to the Cassie state with the increasing depth-to-width ratio of the textures, and the wettability of the interface deteriorates.

Oxidation reaction kinetics of HTPB-boron carbide/polytetrafluoroethylene formulations as a solid fuel

A solid-fuel ramjet engine powered by boron carbide (B4C) can generate nearly the same amount of energy as boron. However, the inherent oxide layer on the B4C surface restricts the energy released during its oxidation. In this study, we examine the effect of polytetrafluoroethylene (PTFE) on the oxidation of B4C and the removal of the oxide layer during the oxidation reaction. The B4C/PTFE binary composite powder was prepared using a ball milling process at three different concentrations (5:20, 10:20, and 15:20). Hydroxyl-terminated polybutadiene (HTPB) loaded with binary composite powder was manufactured by vacuum casting technique. The pure HTPB and HTPB/PTFE fuels were manufactured as reference formulations. The B4C/PTFE binary composite powder was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), and high-resolution scanning electron microscope (HRSEM). The thermal oxidation characteristics of prepared fuel formulations were studied using the thermogravimetric technique. The kinetics of the oxidation reaction was studied using both isothermal and non-isothermal methods. The thermogravimetric curves showed that the oxidation reaction of HTPB-based fuel occurred in four steps. When B4C/PTFE binary composite powder is added to HTPB, it decomposes faster and at a higher rate. The decomposed fluorine species of PTFE significantly improved the oxidation reaction of composite powder and increased the energy release rate of B4C. The kinetic studies of oxidation suggested that the addition of B4C/PTFE binary composite powder into HTPB lowered the activation energy (Ea: S1 > S2 > S3 > S4 > S5) required to prompt the oxidation reaction. Based on thermal and kinetic results, a potential oxidation promotion mechanism of B4C/PTFE composite powder was proposed. The initial stages of B4C oxidation resulted in a glassy layer of B2O3 oxide forming at the interface of B4C and PTFE powder. As a result of the oxidation reaction between B4C/PTFE and O2, CF4, Trifluoroboron (BF3) and CO2 were generated. At high temperatures, the oxide shell ruptured, allowing the O2 to diffuse into the core of the B4C particle and releasing a large amount of heat energy.

Investigation of the microstructure, mechanical and wear performance of friction stir-processed AA6061-T6 plate reinforced with B4C particles surface composite

In this work, friction stir processing (FSP) was used to successfully embed boron carbide (B4C) particles into an aluminum matrix (AA6061-T6). Four specimens of aluminum 6061 composite reinforced with 4%, 6%, 8%, and 10% volume fraction of B4C were manufactured. The effects of B4C particles volume fraction on microstructure, mechanical and wear properties are investigated. The microstructural investigations demonstrated that a rise in the volume % of reinforcement greatly decreased the matrix grain size. The manufactured AA6061-T6 loaded with B4C surface composites demonstrated homogeneous B4C particle dispersion, with no significant particle clustering in the stir zone. In addition, it was established that increasing the volume fraction of B4C particles promoted grain refinement, increased hardness, and tensile strength. X-ray diffraction (XRD) was used to identify the reinforcement dispersion. For AA6061-T6 with 10% B4C particles, a maximum hardness value of 163 HV was obtained in the stir zone. Maximum yield strength of 165 MPa and ultimate tensile strength of 220 MPa were attained by AA6061-T6 with 10% B4C particles, which is an improvement of 21% over the specimen FSP without reinforcement. The strengthening of the grain refining was attributed for the increase in hardness and strength. The ductility was reduced by the incorporation of more B4C particles. Comparing the surface composite loaded with B4C to unreinforced friction stir processing and AA6061-T6 as received, it demonstrated superior wear resistance.

Microstructural and mechanical characterization of functionally graded Fe/Fe2B (Fe/B4C) materials fabricated by in-situ powder metallurgy method

Current study investigates the manufacturability, metallographic and mechanical characterization of the functionally graded Fe/Fe2B composites processed by in-situ powder metallurgy (IPM) using iron (Fe) and boron carbide (B4C) particles. Using powder forms of Fe and B4C particles, the opposite outer surfaces of the FGMs acquired high toughness and hardness, respectively. Moving from one surface which was reinforced with 100 %Fe, the B4C content was gradually increased to reach 20 %B4C providing functional transition from soft to hard surfaces. Three different compositional gradients were used which increased moderately (n:0.1), linearly (n:1), and rapidly (n:5) depending on the content of reinforcement B4C particles within the layers. The functional gradient enhanced the tendency of transition from the metallic to ceramic phases which accelerated with increasing reinforcement ratios. While optical and scanning electron microscopy were used to characterize the microstructure along with the hardness determination of FGMs for each constituent layer, static and dynamic loading behaviors of the FGMs were analyzed by bending and impact tests, respectively. Specimens were loaded from both, 100 %Fe and 20 %B4C surfaces representing the soft and hard sides of the FGMs. Microstructural analyses revealed the presence of Fe2B phases which were in situ synthesized after the B4C reacted with the iron. While the top layer was completely covered by boride phases, it showed the presence of phases even in the lower reinforced layer. Both the fraction of Fe2B phases as well as the hardness of the remaining layers were dictated by the content of B4C particles in the layers. While the hardness of the material was increased due to Fe2B phases, the hardness gradient was also in proportion with the increase in the reinforcement ratios. For each gradient, maximum hardness was achieved for the highest reinforced top layer. The maximum force and fracture energy depended on the surface under force; 100 %Fe or Fe+20 %B4C. FGMs loaded from the 100 %Fe surface showed an overall brittle behavior and those loaded from 20 %B4C surface showed an overall ductile behavior due to load distribution between the hard and soft layer. Additionally, the peak fracture force and fracture energy decreased with the increasing compositional gradients regardless of the types of impacted surface.

Effect of B4C/Gr on Hardness and Wear Behavior of Al2618 Based Hybrid Composites through Taguchi and Artificial Neural Network Analysis

Artificial neural networks (ANNs) have recently gained popularity as useful models for grouping, clustering, and analysis in a wide range of fields. An ANN is a kind of machine learning (ML) model that has become competitive with traditional regression and statistical models in terms of useability. Lightweight composite materials have been acknowledged to be the suitable materials, and they have been widely implemented in various industrial settings due to their adaptability. In this research exploration, hybrid composite materials using Al2618 reinforced with B4C and Gr were prepared and then evaluated for hardness and wear behavior. Reinforced alloys have a higher (approximately 36%) amount of ceramic phases than unreinforced metals. With each B4C and Gr increase, the wear resistance continued to improve. It was found that microscopic structures and an appearance of homogenous particle distribution were observed with an electron microscope, and they revealed a B4C and Gr mixed insulation surface formed as a mechanically mixed layer, and this served as an effective insulation surface that protected the test sample surface from the steel disc. The ANN and Taguchi results confirm that load contributed more to the wear rate of the composites.

Low-Temperature Joining of B4C Ceramics Using Cold-Sprayed Al-8wt%Si Alloy and Microstructure of the Vicinity of the Joint Interface

A series of studies were conducted to demonstrate the feasibility of low-temperature bonding by the forming and heating an Al-8wt%Si alloy thick film on a B4C surface by cold spraying. The results show that: (1) The cracks near the joining interface are closed by the Al alloy by the process studied in this study, and a joining strength of about 220 and 240 MPa is achieved by low temperature joining of 580 °C and 600 °C, respectively.; (2) The amount of weak intermetallic compounds at the joining interface is reduced; (3) It is assumed that the reduction in the amount of Al-B-C compounds is due to the formation of the β phase during the solidification process of the Al-Si alloy, which hinders the growth of the compounds.; (4) On the primary joint surface, a continuous void group is formed in the vicinity of the β phase that surrounds the α phase, causing a decrease in the joining strength.

The dynamic compressive properties of B4C ceramic by plasma spraying multilayer Co/Ni–TiCN coatings

The Co/Ni–TiCN multilayer coatings with two layer, four layer and gradient structure were plasma sprayed on B4C ceramic matrix. The effect of the multilayer structure on the dynamic compressive properties of B4C matrix was investigated. The Co/Ni–TiCN coatings consisted of Co–Ni–Cr–Mo and TiC1-XNX (0 ≤ x ≤ 1) phases. At the strain rate of 700 s−1, the peak stress increased by ∼200% after B4C surface coated with multilayer Co/Ni–TiCN coatings, the energy reflectivity increased by 412% (2 layer), 850% (4 layer) and 847% (gradient), and the energy transmittance decreased by 55% (2 layer), 80% (4 layer) and 83% (gradient). At 1500 s−1, the energy reflectivity increased by 490% (2 layer), 705% (4 layer) and 750% (gradient), and the energy transmittance decreased by 57% (2 layer), 83% (4 layer) and 89% (gradient). Compared with 2 layer structure, the 4 layer and gradient structure exhibited enhanced compressive properties because of the more layer interfaces for the reflection and transmission of the stress waves.

Effect of contact time parameter on wettability and interface phenomena of B4C substrate by Ni–Cr–Si–Fe–B–C filler alloy

In the present research, the wettability of boron carbide ceramic by BNi-1 filler alloy at various contact times from 10 to 40 min has been studied. The results of sessile drop wetting tests showed that the BNi-1 filler alloy could spread well on the B4C surface at 10–40 min. With the increase of the contact time from the lowest time (10 min) to the highest time (40 min), the contact angle stably reduced, showing the enhancement of the spreading. However, by the increase of the contact time from 30 to 40 min, a slight change was observed in the wetting angle (from 21° to 19°). Overall, the appropriate spreading behavior of BNi-1 filler alloy on the B4C substrate can be attributed to the tendency of nickel for the reaction with B4C along with the simultaneous availability of silicon and chromium in the composition of this alloy. The maximum wetting angle of 48° was attained for the specimen with 10 min contact time and the minimum angle of 19° was achieved for the specimen with 40 min contact time. Due to the results, different compounds such as Ni4B3, CrB2, CrB, SiC, and Ni2Si have been observed at the system's interface. Moreover, the higher contact times can lead to the intensification of the system's interactions which can subsequently result in the higher penetration of the elements, the reacted area enlargement, and the formation of diverse microstructures and phases. The wetting experiments' results confirmed the spreading ratio calculations.

Effect of Ti addition on interfacial properties of Al (111)/B4C (0001): A combined experimental and theoretical methods

In this study the mechanism of the effect of Ti addition on the interfacial bonding strength and electronic structure of the Al (111)/B4C (0001) interface are investigated based on first-principles calculations and experimental analyses. The calculations results show that the C-terminated B4C (0001) surface is more stable than the B-terminated surface, and the adhesive strength of the C-terminated Al (111)/B4C (0001) interface is improved with the addition of Ti. The charge amount is increased with the addition of Ti atoms, and a stronger Ti–C polar covalent bond is formed; thus, the bonding strength and stability of the interface are improved. The experimental results reveal that with the addition of Ti, the interfacial bonding between the B4C particles and the Al matrix is improved, and the hardness, tensile strength, and elongation of the composites are significantly improved. The calculation results are not only in good agreement with the experimental results but also provide an important theoretical basis for improving the stability of the Al/B4C system through Ti element addition.

Synergy of B4C@MoS2 hybrid for significantly improved mechanical and tribological properties of PI/PTFE fabric composites

AbstractIn this study, a hierarchical B4C@MoS2 hybrid is constructed by growing MoS2 nanoflowers onto micro B4C (boron carbide) surface via an in situ hydrothermal process. Thereinto, the PDA/PEI (polydopamine/polyethyleneimine) co‐deposition coating covers over the micro B4C surface to serve as the interfacial interlayer responsible for assembling the B4C and MoS2 together strongly. The achieved B4C@MoS2 hybrid is used to strengthen the tribological performance of PI/PTFE fabric phenolic composites. Tests showed that the resultant B4C@MoS2/fabric composites exhibited effective enhancement in hardness because of the outstanding strength and modulus of B4C. Meanwhile, the thermal stability of B4C@MoS2/fabric composites significantly outperformed the MoS2/fabric composites resulting from the excellent thermal and barrier properties of B4C. Moreover, the tribological tests manifested that the wear rate of B4C@MoS2/fabric composites was decreased by 84% compared to that of pure composites. The synergetic enhancement effect between B4C and MoS2 was revealed by worn surfaces and tribofilms analysis. The B4C@MoS2/fabric composites possessed the optimal wear resistance ascribed to the excellent load‐bearing capacity of B4C and lubricating property of MoS2.

Effects of Zr element on the microstructure and mechanical properties of B4C/Al composites fabricated by melt stirring method

In this study, the addition of Zr element (K2ZrF6) was employed to improve the wettability, inhibit the serious chemical reaction of B4C to Al, and uniformly disperse the B4C particles in the Al melt, during the fabrication of B4C/Al composites via melt stirring method. And the particle distribution, interface microstructure and mechanical properties of the fabricated composites were further investigated. The metallography observation shows that the B4C particles could be effectively introduced to the Al melt with the addition of Zr element, while there were few B4C particles observed in the composites without Zr addition. The XRD analysis indicates that the ZrB2 and ZrC peaks arise with the addition of Zr, where the ZrB2 and ZrC have better chemical stabilization and wettability than the B4C ceramic particles. The SEM, EDS, TEM and SAED analysis shows that the ZrB2 and ZrC interface layer with a thickness of about 200–350 nm on the B4C surface was formed, which could avoid the serious chemical reaction and improve the wettability of B4C to Al, simultaneously. In addition, the easy introduction of B4C particles to the Al melt with K2ZrF6, the formation mechanism of ZrB2 and ZrC layer, and mechanical properties of the composites were also discussed.

Adsorptive removal of methylene blue from aqueous solutions by porous boron carbide: isotherm, kinetic and thermodynamic studies

In this study, the performance of boron carbide (B4C) on the adsorptive removal of methylene blue from aqueous solutions was investigated. Adsorption studies were carried out using different adsorbent dosage, dye concentration, pH, and temperature parameters. The BET analysis results showed the B4C surface area is 317.6 m2/g and B4C has a mesoporous structure. From the adsorption studies, the maximum dye removal percentage was obtained as 97.3% at 55 °C. Besides, different isotherm models were used during adsorption and the order was determined as Langmuir > Flory – Huggins > D – R > Freundlich > Harkins – Jura. For the Langmuir isotherm, qm was calculated as 188.68 mg/g at 55 °C. D-R isotherm, enthalpy, and activation energy data showed that adsorption took place physically. The kinetic studies showed that the adsorption was compatible with the pseudo-second-order kinetic model. Besides, it was determined from the thermodynamic studies that adsorption occurs endothermically and spontaneously.

Fabrication of textured B4C ceramics with oriented tubal pores by strong magnetic field-assisted colloidal processing

Highly structure-controlled B4C ceramics were prepared via strong magnetic field-assisted slip casting of a slurry, containing B4C base particles and pore-forming agents with a fiber shape. To achieve gas release at a lower porosity for maintaining its mechanical strength, these B4C ceramics had a structure in which a large number of oriented tubal pores were dispersed in a crystallographically-aligned and dense B4C matrix phase. The B4C microstructure, such as structuration and orientation degree distributions of the B4C grains and tubal pores, was characterized by SEM observation, EBSD analysis, and X-ray CT. Among the investigations, it was found that the oxidic impurities, as an inhibitor of sintering, which existed on the B4C surface, can be removed by ethylation and azeotropy due to an ethanol treatment followed by vacuum drying. Thus, an ethanol treatment of a green compact before sintering was significantly effective for the fabrication of the B4C ceramics, including the microstructure that coexisted with a dense matrix phase with tubal pores. The resultant ceramic specimens showed the remarkable three-point bending strength of 459−554 MPa, which is two times higher when compared to conventional B4C pellets with a similar porosity.

Ultrasound assisted casting method for fabricating B4Cp/Al composites with the addition of K2ZrF6

In this research ultrasound assisted casting method was applied to fabricate 10 wt.%B4Cp/Al composites with the addition of K2ZrF6. The effects of Zr content on the microstructure, including the distribution and the interface of B4C particles, as well as the mechanical properties of composites were investigated. Experimental results showed that an interfacial layer which was composed by nano-sized ZrB2 particles could be formed on B4C surface, which was beneficial for improving the dispersity and hindering the decomposition of B4C particles in the Al melt. As the addition amount of Zr satisfied the ratio of (wt.%Zr)/(wt.%B4C) = 0.2, the B4Cp/Al composites with a homogeneous microstructure had the best comprehensive and most stable mechanical properties.

Investigation of wear and corrosion behavior of graphene nanoplatelet-coated B4C reinforced Al–Si matrix semi-ceramic hybrid composites

The present study aims to produce graphene nanoplatelet-coated B4C ceramic particle using semi-powder method and to investigate the effect of graphene nanoplatelets on wear and corrosion performance of Al–Si-based metal matrix hybrid composites. For this purpose, first graphene nanoplatelets at different ratios (0.25, 0.5, and 1 vol.%) were coated to the surfaces of B4C particles and then the Al–Si alloy was infiltrated into the reinforcements by gas pressure infiltration method. The characterization of graphene nanoplatelet-coated B4C powders and its composites was carried out by X-ray diffraction, differential scanning calorimetry, scanning electron microscope, and transmission electron microscope analysis. Tribological properties were investigated by reciprocating ball-on-flat method under three different loads (10–20–40 N) in a dry environment. The corrosion resistance was carried out with Tafel polarization method in 3.5% NaCl solution. Characterization results show that graphene coated on the B4C surface was successfully achieved by semi-powder method. After infiltration process, a new phase formation was not observed, but porosity increased with the increase of graphene content. When the boron carbide surface was coated with 0.5vol.% graphene, it was determined that the specific wear resistance increased by 55% and the corrosion resistance decreased by 12%.

Wear Characterization of Al/ B4C surface composite produced by TIG arc process

Aluminum-based surface composites were fabricated by the TIG arc process. B4C micro and nanoparticles were filled separately on the grooves of the Aluminum substrate and modified the surfaces with different TIG arc speeds. The modified composite surface was characterized by optical microscope, Scanning Electron microscope, and X-ray diffraction. The microhardness and wear properties of the composite surface were evaluated. The results of this study revealed that the newly formed nanocomposite surface enhances the hardness and wear characteristics. The wear worn-out surfaces of the composite surface were analyzed through SEM studies in order to understand the wear mechanisms

Development of Mild Steel – B4C Surface Composite by Friction Stir Processing

Development of Mild Steel – B4C Surface Composite by Friction Stir Processing

Development of Mild Steel – B4C Surface Composite by Friction Stir Processing

Objectives: Friction Stir Processing (FSP) is being attempted in this study to process the surface layer of mild steel and to explore the possibility of incorporating B4C particle into surface layer of mild steel to form surface composite by means of FSP technique. Methods: FSP with B4C particle was carried out on 5.0 mm mild steel and specimens 250 mm x 100 mm were processed in a single pass. The tool material used was tungsten carbide. Trial runs were carried out at different process parameters and the final parametric windows have been developed for getting the defect free surface. With optimized process parameters sound and defect free surface was made. Mechanical Properties were investigated through microstructure and hardness test. The micrographs and hardness graph have been presented and discussed in this paper. Findings: The Micrographs were taken using optical microscope at different location of the processed zone. There was distinct alteration in size and shape of the grains at different location of the processed area. Temperature in the stir zone is sufficient to convert the base material ferrite into austenite region of phase diagram. Since the recovery is slow in austenite, dynamic recrystallization occurs. The amount of deformation in friction stir processing is very large, therefore the critical condition for discontinuous dynamic recrystallization are met. This leads to very fine austenite grain formation. These fine recrystallized grains of austenite transform back into ferrite when the temperature falls down. Macro hardness test was also done using the Vickers hardness test. It was found that the average hardness has increased to more than three to four times in the processed zone as compared to the parent metal. Applications: Technology developed in this study can be effectively used in several areas like mining, mineral processing, aerospace and railway industry, where surface modification is a need to reduce various losses like wear and corrosion.

Low friction behaviour of boron carbide coatings (B4C) sliding against Ti–6Al–4V

Boron carbide (B4C) is a potential tool coating for machining of titanium alloys due to its high hardness and high temperature stability. In addition, B4C coatings annealed at 600°C, form a layer that acts as solid lubricant leading to a low coefficient of friction, COF, against titanium. This paper shows that a transfer layer consisting of graphite could be established on B4C surface when sliding against Ti–6Al–4V and passivation of graphitized carbon would reduce COF. Ball-on-disk (B4C) type sliding tests were performed in dry air, argon and nitrogen atmospheres (<0.5% RH), and in air with humidity levels varying between 25% and 85% RH. B4C samples were also tested while they were immersed in water, ethanol (C2H5OH) and iso-propyl alcohol (C₃H₇OH). The B4C coatings exhibited high COF values of 0.59–0.65 in dry atmospheres. Sliding under an air atmosphere containing 70% RH reduced the steady state COF to 0.25 and a further reduction of COF to 0.20 was recorded in air with 85% RH. A COF of 0.15 was measured when the tests were carried out in ethanol and 0.07 in iso-propyl alcohol. Low COF values of B4C were attributed to H and OH passivation of the graphitized transfer layers observed by the Raman, Fourier transform and X-ray photoelectron spectroscopy techniques.

Microstructure evolution of 15 wt% boron carbide/aluminum composites during liquid-stirring process

Microstructure evolution of 15 wt% boron carbide particle reinforced aluminum matrix composites (B4C/Al composites) with titanium addition during liquid-stirring process was dynamically characterized in this paper. B4C particles were rapidly dispersed under the mechanical stirring. Many B4C clusters were formed in the melt before 20 min, but gradually scattered in matrix beyond 20 min, owing to further reactive wetting through interface reaction in addition to stirring. After rapid improvement, distribution uniformity slowly approached to completely uniform distribution during 20–55 min, even better than random distribution at 55 min. Interface reaction produced Al3BC, TiB2, and AlB2 by B4C erosion and Al3Ti decomposition; however, AlB2 only precipitated in matrix after long time stirring. The growth of TiB2 transformed from a fine layer to discretely coarse crystals on the B4C surface. Reaction mechanism and relationship between reactive wetting and particle dispersion were discussed.