Copper-coated graphite and copper mixture powders were deposited on AZ31B magnesium alloy and 6061 T6 aluminum alloy substrates under different process parameters by a solid-state cold spray technique. The microstructure of the copper-coated graphite and copper composite coatings was visually examined using photographs taken with an optical microscope and a scanning electron microscope. The surface roughness of the coatings was investigated with a 3D profilometer. The thickness of the coatings was determined through the analysis of the microstructure images, while the adhesion of the coatings was characterized using the scratch test method. The results indicate that the surface roughness of the coatings sprayed on the two different substrates gradually decreases as gas temperature and gas pressure increase. Additionally, the thickness and adhesion of the coatings deposited on the two different substrates both increase with an increase in gas temperature and gas pressure. Comparing the surface roughness, thickness, and adhesion of the coatings deposited on the two different substrates, the surface roughness and adhesion of the coatings on the soft substrate are greater than those of the coatings on the hard substrate, while the thickness of the coatings is not obviously affected by the hardness of the substrate. Furthermore, it is noteworthy that the surface roughness, thickness, and adhesion of the copper-coated graphite and copper composite coatings sprayed on the two different substrates exhibit a distinct linear relationship with particle velocity.

The development process of electrospark deposition (ESD) technology is reviewed, and the principles and differences of ESD technology are discussed in this review. Based on the research status regarding the ESD of titanium alloys, the promotion effect of ESD technology on wear resistance, corrosion resistance, oxidation resistance at high temperatures, and the biocompatibility of titanium alloys was elaborated on. For example, with the use of ESD technology to prepare Ti–Al, TiN, Ni–Cr, and other hardening coatings with high hardness, the maximum hardness of the deposited layer is six times higher than that of the substrate material, which greatly reduces the loss of the material surface in the process of friction in service, and has a high wear–resistance effect. The preparation of a single–phase lamellar coating is more beneficial for improving the oxidation resistance of the substrate. Carbide and a nano–porous coating can effectively enhance the bone integration ability of implants and promote biocompatibility. The application of ESD technology in the surface modification of titanium alloys is reviewed in detail. Finally, the development direction of ESD technology for titanium alloys is proposed.

A temperature and refractive index simultaneous measurement sensor based on an optical microfiber coupler (OMC) combined with a polarization maintaining fiber (PMF) is proposed and experimentally demonstrated. The OMC-PMF sensor is fabricated by inserting a section of PMF between two output ports of the OMC. The interference spectrum of the OMC-PMF sensor has different responses to temperature and refractive index variations. Temperature and the refractive index can be measured by monitoring the dip intensity variation and the dip wavelength shift of the interference spectrum, respectively. The experimental results show that the refractive index sensitivity is 12 020 nm/RIU, and the temperature sensitivity is 0.88 dB/°C upon increasing temperature from 35 °C to 41 °C.

In this article, the studies undertaken on brazed diamond tools were reviewed. The influences of the brazing alloys with different active elements on the brazing quality of brazed diamond tools are emphatically discussed. The differences in the micromorphology, friction and wear properties, and mechanical properties of brazed diamonds caused by three different brazing alloys are described in detail. The quality evaluation of brazed diamond tools is discussed from several aspects, such as the difference in microstructure of the diamond/brazing alloy interface, the friction and wear of brazed diamond tools, and the strength and residual stress of the brazing interface. Finally, relevant open questions related to the brazed diamond tools’ performance are outlined, and the future has been prospected.

Sintering additives are commonly used to reduce the conditions required for densification in composite ceramics without compromising their performances simultaneously. Herein, SiC/SiC_w-Y₂O₃ composite ceramics with 10 vol.% SiC whiskers (SiC_w) and different Y₂O₃ contents (0, 2.5, 5, 7.5, and 10 vol.%) were fabricated by hot-pressed sintering at 1800 °C, and the effects of Y₂O₃ content on the microstructure, mechanical properties, and tribological behaviors were investigated. It was found that the increased Y₂O₃ content can promote the densification of SiC/SiC_w-Y₂O₃ composite ceramics, as evidenced by compact microstructure and increased relative density. The Vickers hardness, fracture toughness, and flexural strength also increased when Y₂O₃ content increased from 2.5 vol.% to 7.5 vol.%. However, excessive Y₂O₃ (10 vol.%) aggregated around SiC and SiC_w weakens its positive effect. Furthermore, the Y₂O₃ additive also reduces the coefficient of friction (COF) of SiC/SiC_w-Y₂O₃ composite ceramics, the higher the Y₂O₃ content, the lower the COF. The wear resistance of SiC/SiC_w-Y₂O₃ composite ceramics is strongly affected by their microstructure and mechanical properties, and as-sintered SiC ceramic with 7.5 vol.% Y₂O₃ (Y075) shows the optimal wear resistance. The relative density, Vickers hardness, fracture toughness, and flexural strength of Y075 are 97.0%, 21.6 GPa, 7.7 MPa · m^1/2, and 573.2 MPa, respectively, the specific wear rate of Y075 is 11.8% of that for its competitor with 2.5 vol.% Y₂O₃.