This study examines the effects of different addition levels of tungsten (W) content on the microstructure, corrosion resistance, wear resistance, microhardness, and phase composition of coatings made from FeCoCrNiAl high-entropy alloy (HEA) using the laser cladding technique. Using a preset powder method, FeCoCrNiAlW_x (where x represents the molar fraction of W, x = 0.0, 0.2, 0.4, 0.6, 0.8) HEA coatings were cladded onto the surface of 45 steel. The different cladding materials were tested for dry friction by using a reciprocating friction and wear testing machine. Subsequently, the detailed analysis of the microstructure, phase composition, corrosion resistance, wear traces, and hardness characteristics were carried out using a scanning electron microscope (SEM), X-ray diffractometer (XRD), electrochemical workstation, and microhardness tester. The results reveal that as the W content increases, the macro-morphology of the FeCoCrNiAlW_x HEA cladding coating deteriorates; the microstructure of the FeCoCrNiAlW_x HEA cladding coating, composed of μ phase and face-centered cubic solid solution, undergoes an evolution process from dendritic crystals to cellular crystals. Notably, with the increase in W content, the average microhardness of the cladding coating shows a significant upward trend, with FeCoCrNiAlW_0.8 reaching an average hardness of 756.83 HV_0.2, which is 2.97 times higher than the 45 steel substrate. At the same time, the friction coefficient of the cladding coating gradually decreases, indicating enhanced wear resistance. Specifically, the friction coefficients of FeCoCrNiAlW_0.6 and FeCoCrNiAlW_0.8 are similar, approximately 0.527. The friction and wear mechanisms are mainly adhesive and abrasive wear. In a 3.5 wt.% NaCl solution, the increase in W content results in a positive shift in the corrosion potential of the cladding coating. The FeCoCrNiAlW_0.8 exhibits a corrosion potential approximately 403 mV higher than that of FeCoCrNiAl. The corrosion current density significantly decreases from 5.43 × 10⁻⁶ A/cm² to 5.26 × 10⁻⁹ A/cm², which suggests a significant enhancement in the corrosion resistance of the cladding coating.

In this study, laser cladding of CoCrFeNiMnTi_x (x is the proportion of the mass of a material, x = 0.0, 0.2, 0.4, 0.6, 0.8) high-entropy alloy (HEA) composite powder coating on 45 steel substrate was studied by using the method of preplaced powder. The phase composition, morphology, microhardness, corrosion resistance and wear properties of CoCrFeNiMnTi_x high entropy alloy were analyzed by XRD, SEM, microhardness tester, electrochemical workstation and reciprocating friction wear tester, respectively. The influences of Ti concentration on structure and properties of CoCrFeNiMn HEA laser cladding coating were discussed. The macromorphology of CoCrFeNiMnTi_x HEA coating layer becomes worse with the increase in Ti quantity. The coating layer is a face-centered cubic solid solution phase. The microstructure of the coating layer is dominated by dendrites and equiaxed crystals. The average microhardness of the coating layer grows with the increases in Ti content, and CoCrFeNiMnTi_0.8 can reach 823 HV. The friction coefficient of the cladding coating gradually reduces and the wear resistance adds as Ti content rises; the friction coefficients of CoCrFeNiMnTi_0.6 and CoCrFeNiMnTi_0.8 cladding coating are similar, at 0.835 and 0.828, respectively. Adhesive and abrasive wear are the two basic types of cladding coating wear. In 3.5 wt.% NaCl solution, the corrosion potential of cladding coating increases with increases in Ti content, the corrosion potential of CoCrFeNiMnTi_0.8 is about 244 mV higher than that of CoCrFeNiMnTi₀, and the density of corrosion current drops to 3.41 × 10⁻⁶ A/cm² from 7.17 × 10⁻⁵ A/cm².

TiC bonded diamond composites were prepared from a mixture of Ti, graphite, and diamond powders as raw materials, with Si as sintering additives, through high-temperature and high-pressure (HTHP) technology. The reaction between Ti and graphite under 4.5–5 GPa pressure and 1.7–2.3 kW output power can produce TiC as the main phase. The diamond particles are surrounded by TiC, and the interface is firmly bonded. The coefficient of friction (COF) of TiC–diamond composites with POM and PP balls decreases with increasing load for a specific friction velocity. However, the COF of TiC–diamond composites with agate, Cu and Al balls increases with the rising load because of the enhanced adhesive wear effect. The COF of PP, Cu and Al balls slightly increases with the increase in friction velocity at a certain load. SEM results show that the surface of agate balls has rough, pear-shaped grooves and shallow scratches. The scratches on the surface of POM balls are wrinkled. The PP balls have pear-shaped groove scratches on their wear surfaces. The wear mechanism of TiC–diamond composites with Cu ball pairs is primarily adhesive wear. The abrasion of TiC–diamond composites with Cu ball pairs remains almost unchanged as the load increases. However, the depth and width of the pear-shaped grooves on the wear surface of TiC–diamond composites are significantly increased. This phenomenon may be attributed to the high rotational speed, which helps to remove the residual abrasive debris from the friction grooves. As a result, there is a decrease in both the depth and width of the pear-shaped grooves, leading to a smoother overall surface. The wear mechanism of TiC–diamond composites with Al ball pairs is abrasive wear, which increases with an increasing load. When the load is constant, as the speed increases, the wear morphology of TiC–diamond composites with Al ball pairs transitions from rough to smooth and then back to rough again. This phenomenon may be attributed to the wear mechanism at low speeds being groove wear and adhesive wear. As the speed increases, the wear particles are more easily removed from the wear track, leading to a reduction in abrasiveness. As the speed increases, the wear surface becomes roughened by a combination of grooves and dispersed wear debris. This can be attributed to the increased dynamic interaction between surfaces caused by higher speed, resulting in a combination of abrasive and adhesive wear. In addition, Cu and Al ball wear debris appeared as irregular particles that permeated and adhered to the surface of the TiC phase among the diamond particles. The results suggest that TiC–diamond composites are a very promising friction material.

Rare-earth oxysulfides are a class of functional ceramic materials with excellent physico-chemical properties and rich functionality. In this study, La₂O₂S powders were prepared from La₂S₃ and La₂O₃ powders at 1000 °C by pressureless sintering. La₂O₂S compacts were synthesized from La₂S₃ and La₂O₃ powders at 800–1600 °C by spark plasma sintering. The influences of sintering temperature and time on the preparation of La₂O₂S were studied. XRD results indicated that La₂O₂S ceramics were synthesized successfully and that the lattice constants of La₂O₂S were close to the theoretical values. SEM showed that the microstructure of La₂O₂S compacts was homogeneous. The specific heat of La₂O₂S mainly came from lattice contribution, and its Debye temperature was 237 K. The UV–visible absorption spectra showed different absorption levels in the 240–300 nm range. Raman spectroscopy revealed distinct peaks at different temperatures, indicating changes in the covalence band. The relative density of La₂O₂S ceramics was 92% and lower than theoretical values. Hardness of the synthesized La₂O₂S was greater than that of Gd₂O₂S ceramics.

Due to their high melting point, low density, and affordable price, TiC ceramics have emerged as one of the most promising ultrahigh temperature structural materials. However, its development and usage are severely constrained by its weak mechanical characteristics. The Ti₂AlC-TiC and Ti₃AlC₂-TiC composites were synthesized by using the laminated metal-ceramic Ti₂AlC/Ti₃AlC₂ as the binder, combined with high-temperature and high-pressure sintering technology (GPa order of magnitude confinement system). The thermal analysis shows that the exothermic heat of Ti/1.2Al/2TiC is less than that of 3Ti/1.2Al/2C, 2Ti/1.2Al/C, and 3Ti/1.5Al/C. The ratio of Ti/1.2Al/2TiC can suppress the thermal explosion phenomenon during the sintering process and improve the safety of the high-pressure sintering process. XRD results showed that the main composition of the sintered products was Ti₂AlC-TiC at 23.5GPa and Ti₃AlC₂-TiC at 45GPa. As the sintering pressure increased from 2GPa to 5GPa, the bonding phase changed from Ti₂AlC to Ti₃AlC₂. The thickness of the synthetic Ti₃AlC₂ layer is near 0.1µm under 5GPa. The average friction coefficient of Ti₂AlC-TiC composites sintered 2GPa with POM is as low as 0.1767, while the average friction coefficient of Ti₃AlC₂-TiC composites with POM increased to 0.34680.3797. The wear width of Ti₂AlC-TiC is lower than that of Ti₃AlC₂-TiC composites sintered under 44.5GPa. The wear width of Ti₃AlC₂-TiC composites decreases following the rise of sintering pressure and is reduced to 0.3504mm under 5GPa. Ti₂AlC-TiC and Ti₃AlC₂-TiC composites with PP ball counterparts have friction coefficients of 0.375 to 0.45 and worse wear resistance than that of POM balls. Ti₃AlC₂-TiC composites synthesized at 5GPa with a Cu ball had the smallest friction coefficient (0.4558) and the smallest wear scar width (0.6289mm). The friction coefficients and wear widths of synthetics with Al pairs ranged from 0.480.697 and 0.8511.087mm, respectively, and varied irregularly with increasing sintering pressure. Ti₂AlC-TiC composites synthesized at 2GPa with agate and glass pairs have coefficients of friction of 0.5 and 0.61, respectively. Abrasion widths of Ti₂AlC-TiC composites synthesized at 2GPa with agate and glass pairs were 1.3mm and 0.72mm, respectively. The friction coefficient of synthetics with agate and glass pairs increases with increasing sintering pressure. The magnetization and magnetization intensity of the Ti₃AlC₂-TiC composites are stronger than those of Ti₃AlC₂. Ti₂AlC-TiC and Ti₃AlC₂-TiC composites held promise to serve in the field of ceramic grinding processing applications.

LiTiO₂ was prepared from tetraethoxy titanium and lithium ethoxide by a sol–gel process and then treated at 773 K and 973 K under oxygen atmosphere, respectively. Compared with LiTiO₂ prepared at 973 K, LiTiO₂ prepared at 773 K has better CO₂ capture properties. XRD patterns of synthetic LiTiO₂ before and after CO₂ capture confirm that the intermediate product, Li_xTi_zO₂, is produced during CO₂ capture. CO₂ absorption degree of LiTiO₂ was determined to be 37% (293 K), 40.8% (333 K), 45.5% (373 K), and 50.1% (393 K) for 11.75 h, respectively. Repetitive CO₂ capture experiment indicates that LiTiO₂ has excellent cyclic regeneration behavior. The CO₂ absorption degree of LiTiO₂ increased with increasing CO₂ concentration. At a concentration of 0.05%, the absorption degree of LiTiO₂ had a stable value of 1% even after an absorption time of 1.4 h. LiBO₂ was fabricated by the similar sol–gel method and treated at 713 K. Mass percentage and specific surface area of synthesized LiBO₂ increased with the increasing absorption temperature. Evidently, the diffusion of the CO₂ molecule through the reaction product, which had a low activation energy of 15 kJ·mol⁻¹ and apparent specific surface value of 55.63 m²/g, determined the efficiency of the absorption reaction. Compared with the other sol–gel synthesized lithium-based oxides, LiTiO₂ possessed higher absorption capabilities and lower desorption temperature.