Whisker Content Research Articles

Performance optimization of novel wear-resistant reflective cooling coatings for asphalt pavement

To enhance the wear resistance of traditional asphalt pavement reflective coatings and extend their cooling effect, this study employed Potassium Hexatitanate Whiskers (PHW) as a functional material to manufacture pavement reflective coatings. It was found that PHW exhibited excellent wear resistance though agglomeration resulted in adverse effects. Therefore, untreated PHW (U-PHW) underwent inorganic-organic surface modification to produce modified PHW (M-PHW). The results indicated that M-PHW exhibited excellent optical properties, with a reflectance of 78.9 %. M-PHW exhibited more uniform dispersion in the resin matrix, which significantly enhanced the coating reflectivity. Moreover, the interfacial bonding strength between M-PHW and the resin matrix was significantly improved, enhancing the wear resistance of the coating. Especially with a whisker content of 16 units, the tensile strength of the M-PHW coating reached 96.20 MPa, representing a 43.0 % increase compared to the U-PHW coating, while achieving a maximum outdoor cooling value of 5.6 °C.

Tribological performance and mechanism of the titanium fiber-SiC whisker hybrid reinforced aluminum matrix composites prepared by pressure infiltration

In this contribution, a Ti-6Al-4V fiber (Tif) and SiCw (SiCw) hybrid reinforced 5056 Al composites (Tif + SiCw/5056 Al) were fabricated, and the effects of SiC whisker contents on the microstructure, mechanical properties, and wear resistance were investigated. The mechanical properties and the hardness of the composites increased first and then decreased with the increase of SiCw contents. The optimal ratio of SiCw to titanium fibers is 3 wt%. The flexural strength of the optimal composites reached 533 MPa, and the fracture toughness reached 29.1 MPa m1/2. Under a load of 40 N, compared with the Tif/5056 Al composites sample, the wear rate of the optimal composites sample decreased by 80.7 %. The uniformly dispersed SiC whiskers promote the formation of a mechanical mixing layer (MML) on the friction surface; the wear mechanism mainly involves abrasive wear and adhesive wear.

Static and dynamic mechanical properties of aluminum nitride-silicon carbide whisker composites

AlN composites reinforced with SiC whiskers and Y2O3 sintering aids were fabricated using the hot-pressing technique to investigate static and dynamic mechanical properties. Microstructure analysis revealed that increasing SiC whisker content yielded grain refinement and decreasing relative density. The Vickers hardness increased from 10.29 to 14.47 GPa, while the fracture toughness improved from 3.03 to 4.39 MPa·m1/2 with 30 wt% SiC whiskers. A numerical approach for evaluating the dynamic modulus and loss factor is presented utilizing the wave propagation characteristics. The dynamic properties showed decreasing dynamic modulus and increasing loss factor with higher SiC content, attributed to increased porosity and interphase boundaries. Thermal conductivity, however, decreased from 139.53 to 49.95 W/m·K as SiC whisker content increased, primarily due to enhanced phonon scattering at grain and interphase boundaries. These findings suggest that AlN-SiCw composites are promising candidates for heat dissipation ceramic substrates, which offer superior mechanical strength and reliable thermal management.

Co-sintering fabrication of ceramic whiskers enhanced SiC membranes for high-efficiency dust-laden gas filtration

Application of silicon carbide (SiC) ceramic membrane in industrial dust-containing gas filtration has been widely explored. However, its limited gas permeance and complex sintering process hinder its application. In this work, two types of SiC whisker-reinforced ceramic membranes, namely, whisker ceramic membranes (WCMs) and whisker/particle composite ceramic membranes (WPCMs), were prepared using a co-sintering process. By optimizing the co-sintering temperature and SiC whisker contents, defect-free and uniform ceramic membranes were obtained. The mean pore size of WCMs was 12.2 μm with a gas permeance of ∼ 478.0 m3·m−2·h−1·kPa−1. The WPCMs exhibited a mean pore size of 3.3 μm with a gas permeance of ∼ 288.0 m3·m−2·h−1·kPa−1. SiC whiskers interlaced and connected within membranes, forming a network structure that not only effectively prevented delamination or deformation of the membrane during the co-sintering process but also significantly enhanced the gas permeance of membranes. Additionally, SiC whiskers improved the overall bending strength of membranes and enhanced the rejection of dust particles in the dust-laden gas. The resulting WCMs and WPCMs showed excellent chemical stability and thermal shock resistance. Moreover, the optimized membranes achieved a removal efficiency of 99.99 % for macro (15 μm), micro (2.5 μm), and nano (300 nm) solid particles in the dust-laden gas. This work fabricated high-performance SiC whisker-reinforced membranes that were particularly suitable for gas purification.

Synthesis, microstructure, mechanical and tribological properties of high-entropy carbides (WZrNbTaTi)C-SiCw

In this work, composite high-entropy carbides (WZrNbTaTi)C-x SiCw (x = 0, 5 %, 10 %, 15 %, 20 %) are prepared using the two-step fast hot-pressing sintering (TSFHPS) method. The whiskers in the samples are evenly dispersed and well integrated with the ceramic matrix, forming high density materials. The mechanical properties and tribological properties at room temperature are studied, revealing that the addition of SiCw improves the performance of the materials. When the whisker content is 15 %, the hardness and fracture toughness of composite ceramics are the highest, which are 22.6 GPa and 6.8 MPa m1/2, respectively. The bending strength of the samples increases monotonically with the increase of whisker content, and reaches 639.2 MPa at 20 % content. At the same time, the addition of an appropriate amount of SiCw prevents the propagation of micro-cracks and the expansion of oxidative wear, thereby reducing the friction coefficient and wear rate, and improving the wear resistance of high-entropy carbides.

Finite element simulations of thermal stress distribution in thermal barrier coatings with different mullite whisker arrangements

In recent years, thermal barrier coatings (TBCs) have been extensively employed to safeguard turbine engine blades against high temperatures and harsh operating conditions. Mullite whiskers are frequently utilized to improve the mechanical properties of ceramic matrix composites because of their exceptional characteristics. This study investigates thermal stress in coating systems by analyzing the impact of varying content, aspect ratio, and deflection angle of mullite whiskers using finite element simulations under static conditions. Results demonstrated that incorporating mullite whiskers can mitigate the sudden stress variation between the ceramic coating and the substrate. The addition of mullite whiskers reduced the maximum stress value in the coating system, thereby enhancing its thermal stability and service life. The arrangement of mullite whiskers was controlled during the preparation procedure to ensure their proper orientation. The coating system exhibited higher mechanical properties at a certain position. This study provided a theoretical basis for the design of mullite whisker–reinforced TBCs.

Elucidating the effect of whiskers on microstructural, mechanical and wear properties of ceramic-metal composites for sports venues applications

Ceramic whiskers reinforced composites are widely used in electrical, medical, and constructional applications due to their desirable strengths, hardness, and wear characteristics. In this study, to examine the wear and friction characteristics, the pressureless infiltrated Cu–SiC composites with different content of SiC whiskers were roll bonded to Al layer. According to SEM images, the SiC whiskers were distributed across the microstructure although they were aligned along rolling direction. Incorporation of SiC whiskers to Cu matrix led to rise of composites’ strengths, young moduli, and hardness values. The measured values of Al and Cu–SiC layers increased from 50 HV to 135 HV in Al/Cu–SiC (5 wt%) to 57 HV and 159 HV in Al/Cu–SiC (15 wt%). Ductile type of fracture along with dimples, delamination, and debonding of whiskers appeared on fracture surfaces. However, more debonding of SiC whiskers was observed as SiC content increased. Accordingly, mass loss decreased and less adhesive wear mechanism was observed. The mass loss decreased from 6.3 mg in Al/Cu–SiC (5 wt%) to 5.2 mg in Al/Cu–SiC (15 wt%).

Digital light processing of high-purity SiC ceramic membrane support modified by SiC whisker

High-purity SiC ceramic membrane has gained tremendous attention in the treatment of various corrosive wastewaters. Additive manufacturing technique makes it possible to fabricate high-purity SiC ceramic membrane with complex configurations. Here, we proposed a route for the preparation of high-purity SiC ceramic membrane support using digital light processing and SiC whisker reinforcement. With the increase of whisker content, the viscosity of SiCw/SiC photosensitive slurry increased due to the formation of whiskers agglomerations; the average pore size shifted from 3.15 μm to 1.35 μm with the occupation of large pores by SiC whiskers. In addition, the compressive strength of the ceramic support increased from 10.7 MPa to 16.7 MPa because of the decline in pore size and the toughening effects by SiC whiskers. So, the introduced SiC whiskers enhanced the pore connectivity and mechanical strength of the porous ceramics. This work provides a feasible path to manufacture high-purity SiC ceramic membrane support with complex configuration, high pore-connectivity and excellent mechanical properties.

Effect of Carbon Fiber and Potassium Titanate Whisker on the Mechanical and Impact Tribological Properties of Fe-Based Impregnated Diamond Bit Matrix.

Various contents of carbon fibers (CFs) and potassium titanate whiskers (PTWs) were added to an Fe-based impregnated diamond bit (IDB) matrix to enhance its adaptability to percussive-rotary drilling. A series of mechanical tests were conducted successively to find the effects of the reinforcing materials on the properties of the Fe-based IDB samples. Then, the fracture surfaces of the samples were analyzed via scanning electron microscopy (SEM) and energy-dispersive spectroscopy, and the worn surfaces and abrasive debris of the samples were analyzed using a laser scanning confocal microscope and SEM. The results show that both the CF and PTW can effectively improve the hardness and bending strength of an Fe-based IDB matrix, and those parameters reached their maximum values at the additive amount of 1 wt%. However, the CF had a better enhancement effect than the PTW. Furthermore, the CF improved the impact wear resistance of the IDB matrix, with a minimum wear rate of 2.38 g/min at the additive amount of 2 wt%. However, the PTW continuously weakened the impact wear resistance of the IDB matrix with increases in its content. Moreover, the morphologies of the worn surfaces indicated that the minimum roughness of the CF-reinforced IDB matrix decreased significantly to as low as 4.91 μm, which was 46.16% lower than that without CF, whereas the minimum roughness of the PTW-reinforced samples decreased by 11.31%. Meanwhile, the abrasive debris of the CF-reinforced samples was more uniform and continuous compared to that of the PTW-reinforced samples. Overall, the appropriate addition of CF or PTWs can enhance the mechanical properties of Fe-based IDB matrices, which can be used on different formations based on their impact wear resistance.

Influence of magnesium and calcium sulfate whisker on crystallization characteristics of poly (butylene adipate-co-terephthalate) and Poly(butylene succinate)

Inorganic fillers of whisker-like morphology are considered promising materials, and they have gained significant attention in recent years as a substitute for glass fibers due to their fibrous surface characteristics and extremely low bulk density. This study selected magnesium sulfate whiskers (MSWs) containing crystal water and pure calcium sulfate whiskers (CSWs) as fillers. They were physically blended with biodegradable polymers PBAT and PBS in a range of 0.1 wt.% to 2 wt.% to form composite materials. The non-isothermal crystallization behavior of the composite materials was studied using differential scanning calorimetry (DSC). The data indicated that with an increase in whisker content, the crystallization temperature (Tc) of composites increased, and the addition of a small amount of whiskers led to a reduction in the half-crystallization time of the composite materials, indicating the crystallization capacity of the materials has been enhanced to varying degrees. Analysis via POM unveiled a consistent pattern of decreased spherulite size and heightened spherulite count with the introduction of whiskers. This phenomenon is ascribed to the whisker fillers’ function as nucleating agents within the polymer matrices, thereby stimulating the crystallization process. Interestingly, the findings suggest that CSWs exert a more significant influence on crystallization than MSWs, likely due to the distinct single fiber morphology of the former filler.

Synthesis of equiaxed Si3N4 from Si(NH)2 by adding seeds formed by in situ nitridation of silicon

High-quality Si3N4 powder is a prerequisite for the preparation of high-performance Si3N4 ceramics. In this paper, Si3N4 powders with regular morphology were successfully prepared by pyrolysis of Si(NH)2 using silicon as a nucleation inducing agent. The mechanism of the silicon in regulating the morphology and particle size of Si3N4 powders was investigated. The results show that when Si(NH)2 is pyrolyzed directly at 1500 °C under N2 atmosphere, the products are mainly whiskers accompanied by some particles with irregular shape. In the presence of silicon, the powder particles exhibit a regular hexagonal prismatic morphology. With the increase of silicon content, the whisker content decreases obviously, and the whisker disappears completely when the silicon content exceeds 10 %. Furthermore, the particle size of Si3N4 powder decreases with the increase of silicon content, and the particle size is the smallest when the silicon content is 15 wt%, which is about 802 nm. The nucleation and growth process of Si3N4 powder particles can be divided into three stages. Firstly, silicon reacts with N2 to form Si3N4 nuclei. Then, amorphous Si3N4 partially decomposes to form Si(g) and SiO(g) and grows on the formed Si3N4 nuclei as the temperature increased. Finally, undecomposed amorphous Si3N4 spontaneously nucleates and grows of the solid-phase diffusion mechanism. Ultimately, all the powders show equiaxial regular morphology. Preferential nitridation of silicon to form Si3N4 nuclei provides nucleation sites for vapor-phase products, which is the key to inhibiting whisker formation and regulating the particle size of Si3N4 powders.

Carbonation resistance of recycled fine aggregate concrete reinforced by calcium sulfate whiskers

This study investigates mechanical and carbonation resistance tests conducted on Recycled Fine Aggregate Concrete (RFAC) with three different Recycled Fine Aggregate (RFA) replacement rates and four calcium sulfate whisker (CSW) contents, and investigates the effects of RFA replacement rate and CSW content on the mechanical properties of RFAC and the carbonation resistance of RFAC with calcium sulfate whiskers at different ages of carbonation. The microstructure of CSW-modified RFAC was observed and analyzed by SEM electron microscopy to explore further enhancement and toughening mechanisms of CSW in RFAC, as well as the optimal content of CSW in RFAC. In addition, the carbonation depth of recycled concrete with calcium sulfate beard is modeled based on a quadratic fitting formulation. The test results show that the mechanical properties and carbonation resistance of RFAC would decrease with the increase of the RFA replacement rate. Incorporating CSW can effectively improve the mechanical properties and carbonation resistance of RFAC. At 60 % RFA substitution, CSW at 2 % content has the most significant effect on the mechanical properties and carbonation resistance of RFAC. Microscopic analysis shows that CSW has a bridging effect at the micro-cracks in the concrete matrix, preventing the creation and expansion of micro-cracks in the concrete matrix, thus improving RFAC mechanical properties of RFAC and resistance to carbonation. The predicted results of the carbonation depth model which are constructed from the test data coincide with the results. We can use them to predict and analyze the carbonation depth of the carbonation resistance of recycled concrete.

Experimental Investigation of the Impact of Blended Fibers on the Mechanical Properties and Microstructure of Aeolian Sand Concrete.

To investigate the effect of hybrid fibers on the compressive strength of aeolian sand concrete, compressive strength tests were conducted on aeolian sand concrete with single polypropylene fibers and aeolian sand concrete with mixed polypropylene fibers and calcium carbonate whisker, and their variation rules were studied. Using scanning electron microscopy and nuclear magnetic resonance, the microstructure and pore structure of specimens were analyzed, and a mathematical model of the relationship between compressive strength and pore structure was established with gray entropy analysis. The results show that the compressive strength of hybrid fiber aeolian sand concrete first increases and then decreases with an increase in whisker content. When the replacement rate of wind-accumulated sand is 80% and the fiber content is 0.1%, the optimal volume content of whisker is 0.4%, and the 28 d compressive strength of whisker is 24.8% higher than that of aeolian sand concrete. The average relative errors of compressive strength at 7 d and 28 d are 8.16% and 7.48%, respectively, using the GM (1,3) model. This study can provide effective theoretical support for the application of calcium carbonate whisker and polypropylene fibers in aeolian sand concrete.

Converting sintering red mud to valuable calcium carbonate whiskers via an innovative magnesium-modified wet carbonation

Sintering red mud (SRM) is an industrial alkaline waste residue generated from the sintering process in alumina production, which is often directly discarded and causes environmental issues. In this study, an innovative magnesium-modified wet carbonation method was proposed to convert sintering red mud to valuable calcium carbonate whiskers using CO2-containing flue gas. The effects of carbonation conditions including temperature, MgCl2 concentration, and duration on the composition, microstructure, and morphology of carbonated products were systematically investigated. It was found that a high whisker content of 60% with an aspect ratio of ∼6 could be obtained under the optimal conditions of 80 °C, 0.4 M MgCl2, and 2 h reaction time. Besides the formation of whiskers, amorphous aluminosilicate gel was also generated during SRM carbonation. The effects of the as-prepared whisker-rich materials as partial cement replacement on the mechanical properties of cement paste were evaluated with 5 wt% replacement, the 28 d compressive strength was significantly improved by 20.5% compared to the control specimen. The effective reinforcement was ascribed to the fibrous whiskers and enhanced interfacial bonding. This method enables high-value utilization of SRM waste and CO2 fixation, providing a green and low-cost approach to producing high-performance cementitious materials.

Toughening mechanism and oxidation resistance of SiC whisker-toughened SiAlCN ceramics

Mechanical alloying and spark plasma sintering were used to prepare dense SiCw/SiAlCN ceramics. The effects of whisker content on the mechanical properties and oxidation resistance were investigated. Compared with SiAlCN ceramic, the fracture toughness of 5 wt% SiCw/SiAlCN ceramic increased by 31.8 % to 5.8 MPa m1/2, which was attributed to crack deflection/branch and SiCw bridging/pull-out. Based on quantitative calculation, SiCw bridging/pull-out increased fracture toughness by 27.8 %. The flexural strength of 5 wt% SiCw/SiAlCN ceramic was 523.2 MPa, which was 26.9 % higher than that of SiAlCN ceramic. The residual strengths of the SiCw/SiAlCN ceramic after 50 h isothermal oxidation at 1500 °C and 50 times thermal cycles from room temperature to 1500 °C were 292.5 and 449.7 MPa. Because of SiAlCN matrix passive oxidation and SiCw active oxidation, a double-layer oxide scale composed of glassy scale and porous scale was formed on SiCw/SiAlCN ceramics. The unoxidized whiskers could remain original morphology and were available to strengthening and toughening.

Analysis of Factors Affecting the Preparation of Mullite Whiskers from Silica-Rich Slag and Application Studies.

This paper presents an in-depth comparative study of the effects of different molten salt systems, catalyst additions, preparation temperatures, temperature rise rates, and holding times on the properties of mullite whiskers during their preparation process, as well as exploring the enhancement of the toughening effect of mullite whiskers on ceramics. The morphology, crystal structure, and composition of the whiskers were analyzed via SEM, XRD, TG, strength tests, etc. The results show that the best-performing mullite whisker was prepared with an aluminum sulfate molten salt system, with the addition of aluminum fluoride catalyst at 4%, a temperature increase rate of 5 °C, a temperature increase up to 850 °C, and a holding time of 5 h, and its aspect ratio reached 20.64. By adding different contents of mullite whiskers and comparing the toughness strengths and wear rates of the silicon carbide ceramics, it was found that the toughness strength of the ceramics was improved by more than 16.5% and the wear rate was lower than 0.4% when the addition of mullite whisker was more than 3%.

SiCw strengthened WC-Y2O3 composite and its electrochemical corrosion in aggressive medium

The mechanical properties and corrosion resistance of binderless tungsten carbide largely determine its performance and lifespan in complex industrial environments. Herein, WC-1Y2O3-xSiCw (x = 0, 0.5, 1, and 2 wt%) was prepared using the hot-press sintering. The mechanical properties of the composite, as well as the corrosion resistance of optimized mechanical properties in an aggressive medium (0.05 M H2SO4 and 1 M NaOH) were investigated. Results showed that SiCw could significantly increase mechanical properties of the composite, but excessive content (2 wt%) leads to whiskers aggregation and lower properties. The flexural strength and fracture toughness are all increased to varying degrees with whisker content. WC-1Y2O3-0.5SiCw possesses the optimal mechanical properties. The Vickers hardness, fracture toughness, and flexural strength are 2331.24 HV30, 8.59 MPa·m1/2, and 1727 MPa, respectively. Electrochemical tests show that the corrosion resistance of the WC-1Y2O3-0.5SiCw in H2SO4 is higher than that in NaOH solution, and its corrosion resistance in H2SO4 solution increases, but that of the NaOH solution decreases with exposure time. Detailed characterization demonstrated that a dense WO3 film forms in the H2SO4 solution, resulting in a flatter corrosion surface. In contrast, the WC phase in NaOH solution dissolves, thus leading to the accelerated corrosion rate.

Hafnium boride whiskers prepared by boro/carbothermal reduction for high-performance electromagnetic wave absorption

In this study, a chloride-assisted boro/carbothermal reduction method was employed to prepare HfB2 whiskers, aiming to address the challenges associated with large-scale preparation of HfB2 whiskers and the development of high-temperature resistant electromagnetic wave absorbing materials. When the precursors were mechanically stirred, the resulting mixture underwent calcination at 1450 °C for 3 h, leading to the formation of single-phase HfB2 whiskers. The as-synthesized HfB2 whiskers showed exceptional resistance to oxidation at temperatures up to 700 °C. The microwave absorption performance and mechanism of the HfB2 whiskers/paraffin composite were also investigated. The results revealed that the composite achieved a minimum reflection loss of −41.29 dB when the HfB2 whiskers content reached 80 wt%, while the widest effective absorption bandwidth of the composite reached 3.6 GHz when the HfB2 whiskers content increased to 82.5 wt%. This work presents a novel candidate for high-temperature resistant materials used in absorbing electromagnetic wave.

Favorable features of a calcium phosphate cement based on a metastable α ̅-tricalcium phosphate and reinforced by hydroxyapatite whiskers

The composition, impurities, ion substitutions, structure, peculiarities in crystallization and compressive strength were studied in the initial stage of setting (for 15 min) of a new cement based on a metastable -tricalcium phosphate and reinforced by various amounts (up to 15 wt%) of hydroxyapatite whiskers. The set cements were apatitic, highly nonstoichiometric with a Ca/P ratio below 1.5. The compressive strength increased more than twice (up to 8 MPa) at a whisker content of 4 wt% and then decreased again with increasing whisker content. The decline was associated with the growth of nanocrystals on the surface planes of whiskers and formation of micropores in the whisker vicinity caused by the consumption of the surrounding mother phase for the growth. It is expected that the micropores are favorable for the surrounding tissue to grow into enhancing the effectiveness of the set cement. The cement can primarily be used as accessible remedies for treatment of slightly-loaded bone defects.

Cross-scale construction of SiC–Si3N4 porous ceramics with superior electromagnetic wave absorption performance

A unique ceramic structure, which comprises whiskers in its pores and is capable of high-performance microwave absorption, has been designed by comnlining a sacrificial template method with catalytic nitriding. The influence of α-Si3N4 whisker content on the composition, structure, electromagnetic properties, and absorption properties of ceramics is also studied. The α-Si3N4 whisker content is controlled by changing the catalyst amount (FeCl2·4H2O). After adding 5 wt% FeCl2·4H2O, the highest α-Si3N4 whisker content is 78.06 %. The minimum reflection loss value of SiC–Si3N4 porous ceramics with thickness of 2.7 mm is −74.09 dB, rendering it superior than that of previously reported SiC-based absorbing ceramics. The supreior absorption performance is attributed to the reasonable structural design. The unique “whiskers in its pores” structure optimizes impedance matching, enhances attenuation loss and interference cancellation at three scales. This work provides new insights and ideas for the design and development of high-performance ceramic-based absorbing materials.