Research Progress of Deck Anti-slip Coatings

With the in-depth advancement of the strategy to build a maritime power, China’s Marine engineering equipment such as offshore oil and gas platforms, deep-water ports, and large ships has developed rapidly. However, the Marine service environment is complex, involving factors such as high salt spray, high humidity, mechanical wear, and strong ultraviolet irradiation, which cause materials to be subject to the combined damage of electrochemical corrosion and physical erosion, thereby leading to the failure of material structure and mechanical properties. Due to its advantages such as economy, durability and engineering applicability, the protective coating system has become a key technical means to ensure the long-term service of Marine engineering equipment. Deck anti-slip coatings can form anti-slip surfaces with high friction coefficients to ensure the safety of facilities and personnel, and are widely used in equipment such as offshore platforms, ship and aircraft takeoff and landing decks, and ferry decks. The deck anti-slip coating not only needs to have a high coefficient of friction, good anti-slip performance and wear resistance; Due to frequent contact with the Marine environment, it is subject to erosion by seawater and moist salt spray, ultraviolet radiation, oil stains and cleaning agents, etc. Therefore, it is necessary to have excellent corrosion resistance, weather resistance, water resistance, oil resistance, acid and alkali resistance, and high adhesion. For the deck of carrier-based aircraft, it must withstand the strong impact force and high temperature generated during takeoff and landing of the aircraft. The coating needs to have wear resistance, impact resistance, resistance to instantaneous high temperature, flame retardancy and durability, etc. This article systematically reviews the research progress of deck anti-slip coatings at home and abroad, and elaborates on their technical key points from two aspects: polymer-based and metal-based deck anti-slip coatings.

1. The Development History of Deck Anti-slip Coatings 1.1 Research Progress of Ordinary Deck Anti-slip Coatings
   As global Marine resource development enters a new stage of rapid progress, the service scale of Marine structural components such as large vehicle and passenger ferry decks, semi-submersible exploration platforms, and floating Bridges on water continues to expand. The open deck structures of these platforms are exposed to the Marine environment all year round, which poses strict technical requirements for the protective coating system. The application of functional anti-slip coatings has become a key common technology for controlling the corrosion rate of deck materials and preventing slip safety accidents. In the development history of anti-slip coating technology, international leading enterprises or research institutions have always held a first-mover advantage. In 1985, the American AAMC Company pioneered the phenolic base/anti-slip granular composite deck anti-slip coating. Since then, many institutions have successively announced different types of deck anti-slip coating products. The hollow glass microsphere/polyurethane composite system developed by MIC Company of the United States has significantly enhanced the anti-slip performance. AkzoNobel’s Interzone 954 is a two-component, low-VOC content, thick paste epoxy system filled with a gradation of flake barite and silica. It can continue to cure even when immersed in water and is suitable for offshore oil platform decks. Hempel 35490 is a solvent-free epoxy coating containing heavy-duty anti-corrosion and anti-slip fillers. It can be applied in a single coat with a thickness of 2.5mm and is suitable for areas such as exposed decks, load-bearing decks, and offshore platform decks. The anti-slip coating technology in our country has gone through three development stages. In the early stage, the anti-slip coating developed by Shanghai Kailin Paint Factory used an epoxy system reinforced with a high content of quartz sand particles, which led to poor overall performance of the coating. It had disadvantages such as easy cracking, crushing or desanding, poor corrosion resistance and short service life. In the 1980s and 1990s, China entered a transitional period for anti-slip coatings, mainly focusing on the research and development of modified epoxy and high-performance polyurethane deck anti-slip coatings. In recent years, Nantong COSCO Kawasaki Shipbuilding has adopted gradient dispersion technology to construct a SiO₂/ carbon fiber hybrid reinforcement system. On-board tests have shown that the coefficient of friction reaches 0.77. In 2020, the Ministry of National Defense Equipment developed a highly wear-resistant and anti-slip coating system with a sandwich structure, composed of epoxy primer, anti-slip layer and topcoat. It features high impact resistance, wear resistance and good interlayer adhesion, providing a theoretical basis for the research and application of new deck coatings. 1.2 Anti-slip coatings for carrier-based aircraft decks
   The deck of carrier-based aircraft serves as a dedicated platform for the takeoff, landing, parking and transportation of various fighter jets. The anti-slip properties of its surface coating directly affect the safety of aircraft takeoff and landing as well as combat effectiveness. High-performance anti-slip coatings need to have excellent wear resistance, high-temperature resistance, anti-slip property, impact resistance and salt spray corrosion resistance, etc., to ensure reliability and durability in complex Marine environments and high-intensity usage conditions. Therefore, both at home and abroad, a large amount of research has been carried out on anti-slip coatings for carrier-based aircraft decks, and various types of anti-slip coatings for carrier-based aircraft decks have been developed. 1.2.1 Research Status Abroad
   In 1961, the United States formulated the first edition of the MIL standard for anti-skid coatings on carrier-based aircraft decks (MIL-D-23000A), which regulated the performance requirements, classification, construction techniques, and quality control of the coatings to ensure that the deck coatings could meet the harsh conditions during the takeoff and landing of carrier-based aircraft. The MIL-P-24667B standard promulgated in 2005 qualitatively defines the key technical indicators, coating classification, construction performance and other contents of anti-skid coatings for carrier-based aircraft decks. The latest version of MIL-P-24667C released in 2008 has added limit indicators for harmful heavy metals in products. In the 1960s and 1970s, the US military began to use metal-based anti-slip coatings. For instance, nickel aluminate anti-slip coatings were applied to the deflect plates of the USS Forster aircraft carrier through thermal spraying technology. After thousands of take-offs and thousands of jet airflows, only minor damage occurred on the surface. In 1972, the United States developed a polyurethane anti-slip coating, which significantly enhanced its service life and application temperature range. In 1980, the Naval Research Institute in Washington developed a two-component epoxy polyamide deck anti-slip coating with titanium dioxide, talcum powder and carbon black added. It has a service life of 12 to 18 months, demonstrating excellent durability and the advantage of not generating fragments when damaged. It effectively reduces the harm to take-off and landing aircraft and can be applied to the deck of aircraft carriers. In 1989, Cambon developed a coating with polyisocyanate as the curing agent and vinyl polyurethane as the base material. It has outstanding resistance to organic solvents and is suitable for parts such as ship decks and carrier-based aircraft decks. The AST Company of the United States has successively developed the MS series of epoxy-based coatings, which are added with diamond-hardness grade alumina wear-resistant fillers. They have excellent high-temperature gas injection resistance and corrosion resistance, and are widely used on the decks of aircraft carriers and ships in the United States. Subsequently, the company developed the solvent-free AS series of anti-slip coatings to address the environmental pollution caused by solvent evaporation. With the in-depth research on deck anti-slip coatings, the American research center has classified them into four types based on construction methods and durability: roller-coated high-weather-resistant deck coatings, roller-coated or trowel-coated deck coatings, roller-coated elastic deck coatings, and spray-coated deck coatings, and has carried out more professional research. At the end of the 20th century, the American TDA Company developed Alumoxanes nanomaterials. These materials react with epoxy and polyurethane to form inorganic/organic hybrid resins, which exhibit high-temperature resistance and wear resistance, effectively preventing damage to the coating caused by the arresting cables of carrier-based aircraft and the tail hooks of fighter jets. In 2003, the Lawrence Livermore National Key Laboratory developed two types of ultra-hard amorphous iron-based metal materials and, based on them, created amorphous metal coatings with excellent corrosion resistance and wear resistance. These coatings were applied to the deck of carrier-based aircraft through thermal spraying processes, forming coatings with undulating textures. From 2003 to 2006, the US Navy invested 500,000 US dollars to form coatings by mixing Al2O3 and high-performance organic resins, and achieved anti-slip and long service life of the coating through roller or trowel application processes. In June 2012, the US Navy developed an anti-slip coating based on two-component siloxane. This coating has good adhesion to metal substrates, and its water resistance and corrosion resistance are superior to traditional anti-slip coatings, with a longer service life. In addition, the French Armament Agency and other departments have provided financial support to the French Shipbuilding Bureau in developing a new type of deck anti-skid coating. This coating has been verified by the Rafale fighter jet and can effectively reduce the load on the landing gear during aircraft landing and ensure a tight fit between the landing gear tires and the deck. The Dutch AkzoNobel company has developed the Intershield series of epoxy-based anti-slip coatings, with a solid content as high as 90%, meeting the requirements of the US military standard MIL-P-24667C and suitable for all carrier-based aircraft decks. The UK has developed a high-performance epoxy resin-based anti-slip deck coating for internal protection, Proreco, which can meet the special requirements of helicopter decks. The polyurethane coatings formulated by German Bayer Company with Desmophen 650 and 651 and HMDI biuret are used on the decks of ships, including aircraft carriers. 1.2.2 Domestic Research Status
   In the early days, China lacked large-scale aviation operation platforms such as amphibious assault ships and aircraft carriers. The related technologies remained at the theoretical exploration stage for a long time, and due to the lack of standards, the research and development progress was slow. With the acceleration of the modernization process of China’s navy, new types of warships such as destroyers, amphibious assault ships and aircraft carriers have been launched one after another, and the demand for deck anti-slip coatings has become increasingly urgent. At the same time, formulating relevant standards for anti-slip coatings on ship decks to provide a basis for the research and development of deck coatings for carrier-based aircraft has become one of the key tasks in the development of China’s naval equipment. Shanghai Kailin Paint Factory developed China’s first deck coating using yellow sand and cement as the base material and adopting the rubber scraper application method. However, it had many drawbacks, such as being easily worn flat, prone to cracking at low temperatures, and easy to peel off. Subsequently, many paint manufacturers attempted to improve by introducing wear-resistant auxiliary materials such as silicon carbide and diamond, as well as base resins like epoxy polyamide or polyurethane, and developed a series of anti-slip paints. Although these coatings have improved performance to a certain extent, their application effect on the deck of carrier-based aircraft is not ideal. In the 1990s, most of the anti-slip coatings used on the decks of shipborne helicopters in our country were epoxy-based anti-slip coatings. However, they had poor weather resistance and impact resistance. After a small number of aircraft take-offs and landings, they were prone to cracking or even breaking, making it difficult to meet the long-term usage requirements. In 1995, the Marine Chemical Research Institute developed the HF-05 helicopter deck anti-skid coating. It adopts a three-layer two-component polyurethane structure, with several millimeters of polyurethane elastomer inserted between the primer and topcoat, significantly enhancing the impact resistance of the coating. It also features excellent corrosion resistance, weather resistance, wear resistance and high adhesion. It marks a new stage in the technology of deck anti-slip coatings in our country. In 2006, the 725 Research Institute of China Shipbuilding Industry Corporation developed a new type of polyurethane deck coating, which consists of primer, intermediate coat and topcoat. The topcoat is made of polyurethane resin. Through special molecular design, the strong polar groups are retained on the coating surface for a long time, thereby significantly enhancing the anti-slip performance of the coating. In 2014, the Naval Equipment Technology Research Institute of our country announced a new type of anti-slip coating. It uses self-synthesized organosilicon modified epoxy resin as the base material, Al2O3 as the anti-slip and wear-resistant granular material, and modified polyurethane heat reflective coating as the topcoat. It has advantages such as good adhesion, impact resistance and wear resistance, and meets the requirements of the US military standard MIL-PRF-24667C. It has also achieved relatively ideal experimental results in the trial use of ships in the southern region.
   The classification and application of anti-slip coatings for deck 2: Anti-slip coatings can be classified into two major categories based on the substrate: polymer-based anti-slip coatings and metal-based anti-slip coatings. Polymer-based anti-slip coatings use polymer resins as the base material and achieve anti-slip functions by adding anti-slip granules, pigments and other additives. The polymer substrate has a good bonding force with anti-slip granules and pigments and other additives, which can effectively withstand the high-intensity impact force generated during aircraft takeoff and landing, and is less likely to have coating cracking and peeling. Metal-based anti-slip coatings use metal as the base material and have the advantages of high thermal conductivity, solvent-free, high friction coefficient and long service life. They are especially suitable for special scenarios such as deflector plates with cooling grooves. The high thermal conductivity of metal-based coatings can effectively dissipate heat and protect the substrate from high-temperature damage. Its high coefficient of friction provides a strong guarantee for anti-slip performance. 2.1 Polymer-based deck Anti-slip coating 2.1.1 Epoxy-based deck Anti-slip coating
   Since the 1960s, research institutions in developed countries have conducted in-depth research on epoxy anti-slip coatings and successfully developed a variety of high-performance modified epoxy-based anti-slip coating products, which have been widely used in real ship tests on various ship decks. The EPOXO 300C anti-slip coating developed by the AST Research Center in the United States By using hard SiO₂ particles as wear-resistant fillers and introducing polyamide to modify the epoxy resin, it features excellent impact resistance and a high coefficient of friction, as well as outstanding corrosion resistance, making it one of the safest deck anti-slip coatings at that time. Parks et al. developed a phenolic-modified epoxy anti-slip coating by adding hydrophobic silicon carbide, silica and alumina particles, which significantly enhanced the impact resistance and high-temperature resistance of the coating. It can effectively resist the high-temperature erosion of engine tail flames during vertical takeoff and landing of aircraft, providing reliable protection for the deck of carrier-based aircraft. Advanced Material System, Inc., USA The produced Amcoat DC 4667 two-component epoxy anti-slip coating has the advantages of high friction coefficient, excellent chemical resistance, low solvent volatility, thick coating and fast drying, and is widely used in flight decks, hangar decks and other parts. Robinson et al. reported a two-component epoxy coating with low heavy metal content, which uses thermosetting plastics instead of metals as fillers, demonstrating advantages such as high durability, low density and high wear resistance, and can be used in scenarios such as flight decks. 2.1.2 Polyurethane-based deck Anti-slip Coating Polyurethane-based anti-slip coating uses polyurethane resin as the base material. Its molecular chain contains ester bonds and double bonds, which endow the coating with excellent wear resistance, impact resistance, chemical resistance, adhesion, and resistance to high and low temperatures. In 1972, the United States developed a new type of polyurethane system deck anti-slip coating, which improved problems such as high curing temperature, poor adhesion and poor wear resistance. The AS2500 environmentally friendly polyurethane anti-slip coating developed by the American AST Company in 1993 has a 100% solid content, avoiding the emission of volatile organic compounds during the application of traditional coatings. The Interthan990 polyurethane topcoat launched by IP Company in 2001 has excellent comprehensive performance and no restrictions on the coating interval. It is suitable for the hull and superstructure parts of ships. The new polyurethane coating prepared by Bayer Company through the polymerization reaction of Desmophen 650 and 651 with HMDI was completed and put into military application from 2006 to 2008. It has good film gloss, chemical resistance, weather resistance and wear resistance, and has been successfully applied to the deck of carrier-based aircraft. In China, Zhu Wanzhang et al. reported a polyurethane deck coating suitable for helicopter take-offs and landings, including epoxy-modified polyurethane anti-corrosion primer, elastic polyurethane intermediate coat and polyurethane topcoat mixed with emery or silicon carbide. It has good elasticity and adhesion, and is not prone to cracking or peeling. It has been applied on 50 medium-sized ships and can withstand the take-offs and landings of thousands of helicopters. The service life is up to 7 years. Liang Youlu et al. developed a polyurethane base deck anti-slip coating by promoting the formation of interpenetrating networks on polymer substrates through synthetic processes and encapsulating zirconia to create a dense network structure. This coating demonstrates outstanding performance in terms of anti-slip properties, adhesion, wear resistance and corrosion resistance. 2.1.3 Silicone Deck Anti-slip Coating Silicone materials have excellent thermal stability and weather resistance, and can maintain good performance in extreme environments. In 1967, the American GE Company developed an organosilicon elastic coating material. By adding reinforcing fillers and sand and vulcanizing it with hydroxyl organosilicon compounds, it was used for deck anti-slip. Although the coating did not fully meet the requirements of ship decks in terms of hardness, impact resistance and adhesion, it laid a foundation for subsequent research. Subsequently, the American Ameron Company developed a high-performance PSX700 silicone-modified epoxy coating, which uses non-aromatic epoxy resin and polysiloxane as the base material and undergoes condensation polymerization reaction through specific additives to form linear organic substances