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I. Introduction In China, a large number of devices operate in special environmental conditions, such as the fields used for oil and gas extraction； The environment for hydropower and road/railway construction ； Our military equipment is stationed in areas such as Hainan Island, Tibet, and Xinjiang, which are considered the \"three areas where troops shall not go\". Equipment maintenance in special environments focuses on rapid restoration of all or part of its operational capabilities on-site, and imposes specific requirements regarding maintenance time, location, standards, and technical conditions. Therefore, it is particularly important to apply emergency repair techniques appropriately, strive to restore the damaged equipment in the shortest possible time, maximize its in-situ regeneration capacity, and improve its operational efficiency. II. Research framework for emergency maintenance technologies of equipment. Emergency maintenance of equipment involves using emergency diagnosis and repair techniques to quickly assess the equipment when it fails and loses its operational capacity, and to promptly repair the damaged parts as needed, so that the equipment can regain all or part of its functions. Its research framework includes emergency repair technologies, materials, processes, equipment, as well as the fundamental theories underlying the application of emergency repairs. Based on the application environment and repair requirements of emergency maintenance techniques, equipment emergency repair methods are divided into fixed-location emergency repair and on-site immediate repair. III. Fixed-location emergency repair technology: Fixed-location emergency repair mainly refers to emergency repairs carried out at the relay level and base level. The environment and conditions for scheduled emergency repairs are superior to on-site immediate repairs; more advanced and complex surface treatment techniques and processing equipment can be used, as well as high-precision mechanical machining. Therefore, both the scope and quality of repairs should be higher than those of on-site emergency repairs. The several advanced emergency repair technologies listed below are worth focusing on for research and promotion. 1. Nanocomposite electrodeposition technology: Nanomaterials possess excellent mechanical properties, and can be used to create ultra-hard, ultra-strong, ultra-tough, superplastic materials as well as high-performance coatings. They not only serve as high-quality raw materials but also enable the repair or remanufacturing of components through surface engineering techniques, resulting in high-performance surface layers for those components. Nanohard powders, represented by nanodiamonds and nanoceramics, possess very high hardness and good high-temperature resistance. By combining nanomaterials with efficient brush plating technology, and under the strengthening effect of the dispersed nanomaterials, the resulting nanocomposite coating exhibits better performance than a pure nickel brush plated coating. Nanocomposite brush plating technology can be used to repair and strengthen surface damage on equipment components; in emergency repairs, it can be applied to components such as rods, shafts, bearings, and bearing shells to seal or improve the fit of their surfaces ； Sealing or fitting surfaces of shell, box, and bushing-type components ； Surface of plate-type components ； The inner surfaces of holes and grooves in components, etc. 2. High-speed arc spraying technology: This technology uses an arc as the heat source and various spraying materials to create coatings with properties such as wear resistance, corrosion resistance, and anti-slip characteristics. It is an important technique for quickly repairing and strengthening worn parts. Compared with conventional arc spraying, the new high-speed arc spraying method has numerous advantages, and it is mainly used for applying thick coatings on damaged surfaces as well as for the corrosion protection of equipment components. 3. Nano-solid lubricant dry film technology: This technology improves the lubricating and wear-resistant properties of solid lubricant dry films by adding nanoparticles with lubricating and anti-wear effects to these films. It enables effective lubrication in special environments where conventional greases cannot be used, and it offers advantages such as no pollution and no oil leakage. Solid lubricating dry films containing nano-alumina materials exhibit 2-5 times higher wear resistance than those without it. Nanosolid lubrication films can be applied to almost all friction components without the need to change their dimensions; they also possess excellent corrosion resistance and dynamic sealing properties, and can help prevent mechanical vibrations and reduce mechanical noise. 4. Rapid scratch filling technology: Different repair techniques can be employed depending on the severity of the scratches on the friction surface. For more severe scratches, surface techniques and materials such as surfacing and functional repair agents can be used ； Slightly minor scratches can be repaired using brush plating technology ； The micro-area pulsed spot welding repair technique can be used in work environments that require speed and simplicity. The micro-area pulse spot welding repair technique is a method that uses micro-area pulse spot welding equipment and specialized materials to rapidly repair damaged areas of components. This technology generates high temperatures through high-energy electrical pulses, causing the filler material to melt on the pre-treated surface to be repaired, thereby achieving micro-regional welding; it enables rapid repair of uneven wear, grooves, and damage at the edges of complex-shaped surfaces. IV. On-site in-situ repair techniques: The techniques for repairing equipment in situ should adhere to the principles of in-situ restoration, practicality and efficiency, minimal maintenance, and portability and speed. 1. Electrodeless welding technology: Used for the rapid repair of fractures, cracks, perforations, and damages in steel structural components. Electrodeless welding technology is an innovative technique that combines welding technology with self-propagating technology. This technique requires no power source, gas supply, or other equipment; at room temperature, it is sufficient to light the welding material with a match, and welding can be carried out relying solely on the heat generated by the combustion reaction of the welding rod. The welding material is compact and lightweight, easy to operate, and efficient; it can be used by ordinary maintenance personnel. It allows for quick and simple welding of metals of the same type or different types, with the tensile strength of the welds exceeding 300 MPa. This technology is highly suitable for emergency repairs of equipment in field conditions, and it represents an effective method for carrying out on-site repairs of such equipment. 2. Structural patch repair technology: Damage such as cracks and holes in the thin-walled components of equipment can be repaired using structural patch repair technology. Rapid repair technology using composite patches has become one of the key areas of focus in rapid repair technologies in developed countries. The newly developed room-temperature photosensitive curing structural adhesive in our country allows for the repair of a damaged area in no more than 15 minutes; the strength of the repaired area is 50% higher than that of riveted joints, and its fatigue strength is more than 10 times higher than that of riveted joints. The newly developed rapid photopolymerizable patch can be applied directly to repair damaged holes; its curing time is no more than 30 minutes, and its shear strength after curing ranges from 16 to 25 MPa. It can be used within a temperature range of 50 to 100°C for emergency repairs of damaged equipment. 3. Wear-resistant repair technology: Wear, scratches, and corrosion on equipment components can be rapidly repaired using wear-resistant repair technology. The metal repair materials used in this technique are polymer composites that incorporate metals, alloys, ceramics, and anti-friction materials as reinforcing elements. Different reinforcing materials can be added according to various application requirements, resulting in excellent mechanical properties and wear resistance. After curing, it can undergo various mechanical processing operations such as turning, milling, drilling, and grinding, with a compressive strength of 80–12 MPa. This type of composite repair material can be used to repair equipment and components under conditions of frictional wear; its wear resistance is 2–8 times that of ordinary metals. It is easy to use and can be shaped in any desired form. 4. Surface-sealing technology: This technology relies on the surface of the equipment or components to be sealed as a support, with a removable coating applied directly to the surface to be protected. Once the coating cures, it forms a layer that possesses a certain level of adhesion strength while still being removable. The shielding effect of the coating isolates the environment from the surface to be protected, thereby effectively preventing harmful substances in the environment from eroding the surface and achieving the purpose of sealing and protection. Sealing the holes and gaps that connect the surface to the interior of the device with a suitable sealing material will prevent water and air from entering it. V. Development trends of emergency repair technologies. Equipment emergency repair has evolved from traditional methods such as machining and part replacement to the comprehensive use of various advanced emergency repair techniques, moving in the direction of speed, automation, intelligence, and informatization. 1. Strengthen the integration of emergency repair technology and information technology. The development of information technology provides powerful tools and means for emergency repair technology. For example, information technology can be utilized to network emergency repair technologies in order to achieve resource sharing ； By utilizing remote technical support systems, technical experts located away from the damaged equipment can monitor and diagnose it, and provide repair strategies and guidance to carry out repairs, thereby enabling remote, real-time maintenance ； Utilize computer technology to achieve virtual maintenance, thereby saving maintenance resources. 2. Strengthen research on new materials for emergency repairs. The development of material science, particularly research on various new materials such as nanomaterials and composite materials, provides strong technical support for emergency repairs of equipment. The emergence of surface coatings with properties such as high wear resistance, excellent corrosion resistance, heat tolerance, low friction, high adhesion, rapid curing, and high barrier properties, along with their combined use in conjunction with alloys, ceramics, cermets, intermetallic compounds, and polymer materials – especially when integrated with nanotechnology – has improved the level of technology used for emergency repairs of equipment. 3. Expand the scope of application of emergency repair technologies. Traditional repair techniques focus on fixing mechanical components; however, with the development of mechatronics, there has been an increase in electronic devices, and the repair of such devices as well as software has become an important aspect of emergency repairs. Therefore, it is necessary to broaden the scope of emergency repairs and develop technologies for repairing electronic devices and software. References: Xu Binshi, Liu Shicen. 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