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Recent Surface Treatment Technologies and Their Development Trends: An Overview of New Surface Treatment Techniques and Their Development Trends – I. Technical Overview. New types of surface functional coating technologies, including low-temperature chemical surface coating techniques and ultra-deep surface modification techniques, utilize physical, chemical, or physicochemical methods to alter the composition and structural organization of the surface of materials and their components. These techniques preserve the inherent properties of the base material while endowing the surface with the various properties required for specific applications, thereby meeting the particular demands placed on materials in various technical and operational environments. As such, they represent one of the most dynamic fields within manufacturing and materials science, and they are also an interdisciplinary field that combines surface treatment and coating technologies. Its greatest advantage lies in its ability to create high-performance surface layers with properties that are difficult or even impossible to achieve using conventional matrix materials, with minimal consumption of materials and energy; this enables significant economic benefits, making it an excellent and efficient technique for surface modification and coating. High-quality and efficient surface modification and coating technologies have a wide range: such as thermochemical surface techniques ； Physical vapor deposition ； Chemical vapor deposition ； Physical chemistry vapor deposition technology ； High-energy plasma surface coating technology ； Diamond thin film coating ； Multi-layer composite coating technology ； Surface modification, coating performance prediction, and pruning techniques ； Performance testing and life cycle assessment, etc. The new low-temperature chemical vapor deposition technology incorporates plasma enhancement to reduce the temperature to below 600 degrees, enabling a new process for creating hard, wear-resistant coatings. The high-strength, high-performance coatings produced by this process are particularly useful in applications that involve high speeds, heavy loads, and difficult machining conditions. Ultra-deep surface modification technology can be applied to the vast majority of heat-treated and surface-treated parts. It can replace processes such as high-frequency quenching, carbonitriding, and ion nitriding, resulting in a deeper diffusion layer, higher wear resistance, a significant increase in product lifespan, and breakthrough improvements in functional properties. II. Current Situation and Domestic and International Development Trends With the development of basic industries and high-tech products, there is an increasing demand for high-quality, efficient surface modification and coating technologies. Driven by mutual advancement between this field and related disciplines both domestically and internationally, breakthroughs have been achieved in areas such as “thermochemical surface modification,” “high-energy plasma surface coating,” “diamond film coating technology,” as well as “simulation of surface modification and coating processes and prediction of their performance.” 1. Current status and development trends of thermochemical surface modification technologies. In recent years, foreign countries have placed emphasis on research into techniques such as carburizing and carbonitriding under controlled atmosphere conditions and in vacuum, and these techniques have already been put into industrial use. However, it is rarely used in our country, and there is insufficient research on related technologies. Controlled atmosphere carburizing and vacuum carburizing technologies significantly shorten the production cycle, save energy and time; they also improve the quality of the workpieces by preventing oxidation and decarburization, ensuring that the part surfaces have corrosion resistance and fatigue resistance. Additionally, they reduce the amount of machining required after heat treatment as well as the time needed for cleaning. Currently, research achievements in international fields such as carbon potential control and monitoring, as well as the control of the distribution pattern of the diffusion layer, have been applied in actual production, with computer-based online dynamic control being utilized. 2. Current status and development trends of PVD, CVD, and PCVD technologies. Various vapor deposition techniques are challenging research topics that renowned research institutions and universities around the world are competing to explore. Currently, this technology is widely used in industries such as information technology, computing, semiconductors, and optical instruments, as well as in the manufacturing of electronic components, optoelectronic devices, solar cells, and sensors. In the machinery industry, it is also employed in the creation of hard, wear-resistant coatings, corrosion-resistant coatings, thermal barrier coatings, and solid lubrication coatings. The widespread use of coated cutting tools such as those made with TiN has triggered a revolution in the field of machining. Research on diamond films and cubic boron nitride films is also active, with efforts being made to put them into practical use. Based on various PVD and CVD processes, these technologies are continuously taken to new heights through the development and integration of many new processes and equipment, such as IBAD, PCVD combined with hollow-cathode multi-arc composite ion plating systems, devices that combine ion implantation with oil-sputtering or evaporation plating, and plasma-immersed ion implantation systems. Compared with developments abroad, although more research has been conducted in these areas in our country, the level is quite different, and the gap in terms of practical application is even greater. 3. Current status and development trends of high-energy plasma surface coating technology. This technology is used to enhance physical and chemical reactions on the surface in order to obtain coatings with special properties. At its core is more effective enhancement and control of the generation and effects of cathode arc plasma, and the United States, Japan, and Germany are vigorously developing this technology. Plasma-enhanced electrochemical surface modification technology is a field that is currently undergoing active research and development worldwide. For materials such as aluminum and titanium, this technology utilizes plasma-induced discharge to enhance the effectiveness of electrochemical treatment, resulting in the formation of dense layers of alumina and other oxide ceramic films on the metal surface. This enables the substrate to possess surfaces with excellent properties, and it represents cutting-edge technology in advanced manufacturing processes. It also holds great potential for application in the industries of machine tools and molds. 4. Diamond film coating technology: Diamond possesses excellent physical properties. By depositing a thin layer of diamond film on the surfaces of tools, molds, drills, and other components with complex shapes, it is possible to improve their performance and meet the requirements of certain special conditions. In recent years, due to the excellent properties of diamond films and their broad application prospects, Japan, the United States, and Western Europe have carried out extensive research efforts and developed various diamond coating techniques, sparking a surge in research on diamond coatings both domestically and internationally. In particular, foreign countries have made breakthrough advances in key areas such as improving the bonding strength between diamond coatings and substrates, developing technologies for rapid deposition of diamond coatings over large areas, and creating equipment systems for the industrial production of coated diamond films. Countries like the United States and Sweden have already entered the market for diamond-based metal cutting tools, while in China this technology has not yet reached a practical level, and there is an urgent need to develop it and bring it to industrial application. 5. Current status and development trends of multi-component multi-layer composite coating technology. Single surface coatings cannot meet the stringent requirements in surface engineering design; every type of surface treatment has its own advantages and disadvantages. Therefore, it is highly significant to form multi-component multi-layer composite coatings (including gradient layers with gradual transitions) on the substrate surface by utilizing the advantageous properties of different coating materials. Abroad, research has been conducted on multi-layer composite coating technologies featuring a nanoscale thickness for the single layer and over 100 layers in total. The coatings produced exhibit high corrosion resistance, toughness, and strength; they also have good adhesion to the substrate, along with a low surface roughness, which is advantageous for high-speed precision machining. It has been identified as a key area for development abroad, and new breakthroughs are expected in the research and application of nanoscale precision coating materials. Since composite coating technology possesses properties such as wear resistance, resistance to high-temperature oxidation and corrosion, and heat insulation, it can expand the range of applications for coated products and extend their service life; it is a technology that is set to develop rapidly in the coming century. Research has already begun in our country, and initial results have been achieved, but there are still some issues that need to be resolved. 6. Current status and development trends of surface modification, coating process simulation, and performance prediction. As an important part of surface engineering, surface modification and coating technologies have penetrated into both traditional industrial sectors and high-tech industries; meanwhile, the requirements of various applications drive further advancements in surface functional coating technologies. According to usage requirements, designing the material surface and tailoring its surface property parameters to meet specific demands, as well as predicting the microstructure and properties of the surface coating, have become important research directions in this field. Computer simulation studies have been conducted abroad on CVD, PVD, and other surface modification methods. For the CVD process, macroscopic and microscopic multi-level models are used to simulate and predict various properties of the coating as well as the adhesion strength to the substrate ； Through computer simulations of processes such as carburizing and nitriding, as well as the properties of the coatings formed on the workpieces, it is possible to better control and optimize these manufacturing processes. Research in this area in our country is still in its initial stages. III. Goals for the 10th Five-Year Plan and Key Research Areas 1. Goals: Based on the development of surface functional coating technologies both domestically and internationally, and taking into account the needs and current situation of the machinery industry, it is necessary to develop a range of advanced and applicable key technologies for surface functional coatings for use in major projects and key technical equipment. 2. Main research contents: (1) Research on new low-temperature vapor deposition technologies and equipment. Development of new magnetron sputtering, ion plating, and PCVD devices as well as their combined systems, along with the implementation of automatic control over the processing processes. Strengthen research on film formation and the mechanism of adhesion between the film and the substrate, reduce the film-forming temperature, optimize the reaction process and process parameters, and synthesize various new high-quality coatings with wear and corrosion resistance. The focus is on addressing the pressing surface engineering challenges in **safety and key industrial sectors, with the aim of achieving innovative scientific and technological results that will drive technological progress in industries such as general machinery, valves, cold-working molds, and high-temperature molds. (2) Research on nanoscale multi-layer composite coating materials and processing technologies: Keeping up with international advanced levels, this research focuses on nanoscale composite coating technologies and materials with 50 or more layers, including the comprehensive design of the recombination, structure, thickness, and number of layers in such nanoscale multi-element composite coatings, as well as the study of the microstructural characteristics of these coating materials and their manufacturing processes. (3) Research and development on numerical simulation and optimal control of surface coating processes and quality, with a focus on process simulation and optimization of thermochemical surface modification processes as well as PVD and CVD deposition techniques. Mathematical models and algorithms are developed, along with corresponding computer software systems, to guide and analyze the design of surface modification and coating processes, as well as to predict surface properties and service life. (4) Diamond film coating technology: Conduct research on processes for producing large-area, high-speed, high-quality diamond film coatings, as well as on the industrialization of coated cutting tools. The focus of this research is on achieving good coating quality, uniformity, and stable performance. Efforts are made to increase the deposition rate of diamond coatings, and the design and manufacture of corresponding equipment are carried out. Additionally, cutting tools such as diamond film-coated blades and cemented carbide drills are developed, which increase tool life by 10 times; these tools are used in industries such as automotive manufacturing.