Basalt fiber (BF) has a high mechanical strength, excellent temperature resistance, good chemical stability, low energy consumption, and an environmentally friendly production process. In addition, BF-reinforced polymers (BFRPs) have good corrosion resistance and designability; thus, they meet the application requirements of electrical equipment, such as new conductors, insulating pull rods, and composite cross-arms. However, there are still a series of technical issues in the mass production of BF, and the stability of the products needs to be further improved. Therefore, the research on the production, modification, and application of BF is necessary. This paper discusses the chemical composition and production technology of BF, describes the morphology and properties of BF, summarizes the interface problems and modification methods of composites, and finally, introduces the application prospects of BF in the field of electrical materials, which is expected to provide a reference for the application and promotion of BFRP in the future.

The injection and accumulation of space charge in the bulk of XLPE insulation will be intensified due to the ageing of HVDC cable insulation which will affect the normal operation of the HVDC cable. In this paper, the effects of thermal stress of different endurance time and temperature on the space charge distribution of HVDC cable were studied. The samples used in the tests were all slices of 160 kV DC cable insulation and the thermal stress temperatures were 90 and 135 °C, which represented the low temperature thermal stress and high temperature stress, respectively. The Pulsed Electro-Acoustic (PEA) method was used to measure the space charge accumulation and decay characteristics of the samples. And then, the electron trap properties of the test samples were analyzed based on the PEA space charge decay model. Meanwhile, in order to further understand the influence of thermal stress on the physicochemical property of the samples, Fourier Transform Infrared Spectrum (FTIR) and Differential Scanning Calorimetry (DSC) tests were conducted in this paper. The results showed that the 90 °C thermal treating could help to improve the crystalline morphologies of the XLPE at the early stage which led to the decrease of electro traps and space charge density. However, for a much longer thermal stress, the total amount of space charge would trend to increase with the gradually degradation of the XLPE caused by long term thermal stress. Besides, the high temperature thermal stress of 135 °C caused the rapid degradation of the XLPE molecular structure, reducing the crystallinity, creating more deep traps in the insulation and resulting in the accumulation of space charge. With more deep electron traps, the de-trapping process became much more difficult and slower.

Basalt fibre composite materials have shown good application prospects in electrical equipment, but their reliability can be affected by damp‐heat ageing. In this work, the interface, mechanical, and electrical properties of basalt fibre composites treated with three coupling agents via damp‐heat ageing were compared. Molecular simulations were conducted to reveal the damp‐heat ageing mechanism of the composites. The results show that γ ‐aminopropyl triethoxy silane (KH‐550) and γ ‐glycidoxy propyl trimethoxy silane (KH‐560) perform better as coupling agents as they form bonds with the matrix resin, compared with γ ‐methacryloxy propyl trimethoxy silane (KH‐570). After the damp‐heat ageing treatment, the hydrolysis of the defects of the amino groups in the interface of the KH‐550‐treated sample can weaken its mechanical properties and insulation properties greatly. The interface layer of the KH‐560‐treated sample is mostly composed of carbon–oxygen single bonds and methylene groups with its interface structure more stable, which endows the sample with better stability of its mechanical and insulating properties. Therefore, KH‐560 is a more suitable coupling agent for processing basalt fibres to be used in electrical equipment.

Basalt fiber (BF) has high mechanical strength, good insulation performance and low cost. It is suitable to be used as reinforcement material in the manufacture of electrical equipment. However, the large surface inertia of basalt fiber makes it difficult to combine with the matrix material, which seriously limits its service life and application scenarios. In addition, the serious vacancy in the research of insulation properties also limits its production and application in the electrical field. Therefore, in order to solve the problem of difficult bonding between basalt fiber and resin matrix and make up for the research blank of basalt fiber composites in insulation performance, this paper provides a basalt fiber modification method—SiO₂ coating, and tests the insulation and mechanical properties of the modified composite. We used nano-SiO₂ coating solution to modify basalt fiber, and manufactured BF/resin composite (BFRP) by hand lay-up and hot-pressing technology, and experimentally analyzed the influence of nano-SiO₂ content on the mechanical and insulation properties of the modified composite. Fourier transform infrared spectrum and scanning electron microscope analysis showed that nano-SiO₂ was successfully coated on basalt fibers. Through the microdroplet debonding test, it was found that the IFSS of fiber/resin was improved by 35.15%, 72.97 and 18.9%, respectively, after the modification of the coating solution with SiO₂ concentration of 0.5%, 1% and 1.5%, showing better interface properties; the single fiber tensile test found that the tensile strength of the modified fiber increased slightly. Among all composites, 1 wt% SiO₂ coating modified composites showed the best comprehensive properties. The surface flashover voltage and breakdown field strength reached 13.12 kV and 33 kV/mm, respectively, which were 34.6% and 83% higher than unmodified composite. The dielectric loss is reduced to 1.43%, which is 33.8% lower than the dielectric loss (2.16%) of the untreated composite, showing better insulation ability; the tensile strength, bending strength and interlaminar shear strength were increased to 618.22 MPa, 834.74 MPa and 16.29 MPa, respectively, which were increased by 53%, 42.4% and 59.7%, compared with untreated composites. DMA and glass transition temperature showed that the modified composite had better heat resistance. TGA experiments showed that the resin content of the modified composite increased, and the internal structure of the composite became denser.