Abstract: This paper studies the main production processes and characteristics of powder metallurgy, analyzes its main application status in the shipbuilding industry, and compares it with traditional processes in terms of technology and economy. It also looks forward to the application of powder metallurgy technology in the shipbuilding industry.
Keywords: Ship; Powder metallurgy; Manufacturing; Spray coating
With the development of processing and manufacturing technology, traditional material manufacturing processes and technologies are no longer able to meet the growing requirements for the performance of marine materials, especially for materials used under high temperature, high pressure, strong corrosion, and difficult lubrication conditions. Therefore, various new material processing technologies have emerged one after another, and powder metallurgy is one of the most in-depth and widely applied technologies among these new technologies. Its products and technological processes are widely used in industrial fields such as aviation and navigation, automobiles, machinery, hardware, weapons, electronic information engineering, etc. It is known as the "popular component forming technology of Z today" and the "forming technology of the 21st century". Powder metallurgy technology has also been fully applied and developed in the shipbuilding industry, playing a significant role in the development of the world's shipbuilding industry, especially in China's shipbuilding industry. It has even been applied in ships and shipborne weapons.
I.Introduction to Powder Metallurgy
Powder metallurgy is a process of manufacturing metal materials or composite materials using metal powder or a mixture of metal and non-metal powders as raw materials, through various forming techniques and sintering methods. Modern powder metallurgy technology mainly includes the preparation technology of ultrafine powder, rapid solidification technology, mechanical alloying technology, spray deposition technology, powder special forming technology, powder special sintering technology, self propagating technology, and powder injection molding technology. Compared with traditional manufacturing processes, powder metallurgy has the following characteristics:
In powder pressing and injection molding, the material utilization rate is nearly 100%, which can achieve powder near net forming technology, save energy and raw materials, and meet the energy-saving and environmental protection requirements of the new century.
Special purpose materials that cannot be manufactured by traditional processes or are difficult to manufacture can be manufactured, such as using powder metallurgy technology to press oil bearing and compressor crankshaft dynamic sealing ring, meeting market demand.
It can avoid component segregation caused by traditional casting and forming processes.
It can be used as a method for preparing new materials, such as amorphous and nanomaterials.
The use of powder metallurgy technology can modify the surface of traditional materials to improve their physical and chemical properties. For example, powder spraying technology can make metal or non-metal surfaces wear-resistant, corrosion-resistant, and magneto electric resistant.
II. Application of powder metallurgy in the shipbuilding industry
2.1 Application of Powder Metallurgy in Marine Machinery
Powder metallurgy hard alloy can be used for various ship pump parts, such as pistons, filters, etc. Powder metallurgy ceramic parts can be used for ceramic turbine components, such as moving blades, stationary blades, burner cone noses, etc. Some parts of marine diesel engines can also be manufactured using powder metallurgy technology.
Various oil containing self-lubricating bearings manufactured by powder metallurgy can be widely used in various difficult to lubricate and non lubricated marine machinery and equipment. Due to the complexity of marine equipment, harsh operating environments, and limited placement space, the replacement of many equipment parts is extremely difficult. Therefore, it is required that the equipment should have good friction and wear resistance, and be able to maintain excellent wear resistance even when lubricating oil cannot be used. The metal based oil containing self-lubricating material produced using powder metallurgy technology has excellent self-lubricating function, can self-lubricate under various usage conditions, and has excellent anti-corrosion and high-temperature resistance performance. It can be used as self-lubricating bearings in marine machinery and equipment. Parts formed by powder injection molding can be used on various marine machinery and equipment. Powder injection molded stainless steel parts can be used as small marine mechanical parts, such as bearing cages, various valve components, etc.
Compared with traditional process materials, materials made of titanium alloy have good friction and corrosion resistance, making them ideal structural materials for ships.
2.2 Application of Powder Metallurgy in Marine Electrical Equipment
The general marine power supply is DC, so motor brushes are used in motors. In the current manufacturing process, electric brushes are mostly manufactured using powder metallurgy pressing technology. According to the usage requirements of marine motors, different metal or non-metallic elements can be added appropriately to meet the climate corrosion and vibration requirements of marine motors during operation.
Magnets in various marine equipment, especially DC electrical equipment, can also be produced using powder metallurgy. Compared with traditional processes, magnets made by powder metallurgy have uniform magnetic force distribution and permanent magnetism. When used in marine radar and navigation equipment, they have better performance than magnets made by traditional processes.
Various marine temperature detection components, Fiver communication components, camera components, and other components that are not suitable for forging or cutting can be manufactured using powder metallurgy injection molding technology.
2.3 Application of Powder Metallurgy in Shipborne Weapons
The parts manufactured through powder metallurgy technology have been successfully used in the weapons industry. The heterosexual complex parts in modern weapons, such as those processed through traditional machining, precision casting, welding and other processes, not only have complex processes and difficult to ensure machining accuracy, but also complex parts are often difficult to process. The use of powder injection molding technology can reduce costs, ensure accuracy, and reduce processing steps. At present, the weapon components manufactured using this technology mainly include those used in various weapons such as cluster arrows, firearm triggers, firearm safety plugs, bullet cores, armor piercing bullet cores, high-density tungsten balls, missile tails, and bullet safety device spindles. Some small hand light weapons can also use injection molding technology, and their products have passed performance quality certification. After actual testing, the product has excellent performance, stable quality, and reduced production costs. This technology has a huge promoting effect on improving the quality of military weapons and equipment and increasing the cost-effectiveness ratio of military expenses.
2.4 Application of Powder Metallurgy in Ship Repair Industry
The use of powder spraying technology for surface modification and repair is currently one of the most popular processes. During the spraying process, small metal or non-metallic powder coating materials are in a melted or semi melted state and deposit at a certain speed onto the surface of the sprayed object, forming a coating on the surface, thereby enabling the sprayed material to achieve various new functions such as high temperature resistance, corrosion resistance, electromagnetic resistance, and wear resistance. The materials used for spraying are extensive, and almost all solid engineering materials can be sprayed.
Due to the special climatic conditions used in ships, the surface performance requirements of marine metals are very high. Spraying can be used for anti-corrosion of ship structures. Compared with traditional anti-corrosion processes, thermal spraying anti-corrosion reduces maintenance and repair costs, reduces the workload of ship maintenance, and increases the service life of ship steel plates. The arc spraying technology can be applied to the repair of stainless steel oil cooling sleeves for ships. The experimental results show that the use of arc spraying technology, under certain process parameters, to repair marine stainless steel oil cold sleeves, combined with reasonable spraying process and material matching, has achieved good repair results. The research on coating design and process selection for thermal spray repair of marine shaft parts has also achieved preliminary results. Marine parts are mostly shaft type parts. If these parts are repaired using thermal spraying technology, it can save time and reduce costs. The United States, United Kingdom, Russia and other countries widely use thermal spraying technology in the repair of ship shaft parts, and the usage is good. China is currently actively promoting the application of thermal spraying technology in the repair of shaft parts. High speed arc spraying technology can be used in the repair of ship stern shafts. When using thermal spraying technology to repair the tail shaft, this process involves issues such as coating preparation method and selection of coating materials, determination of coating thickness, main process of thermal spraying, and coating processing. The experimental ships repaired using this method have two tail shafts repaired and loaded onto ships using high-speed arc spraying 3Cr13 coating material. They have been in use for more than 3 years and have shown good results. The experiment has confirmed that using thermal spraying technology to repair ship tail fins has advantages such as reliability, speed, and economy.
Marine engine blades, propeller blades, etc. are used in environments with strong corrosiveness and require regular maintenance and repair. The powder thermal spraying repair process has achieved significant results in practical applications. The patented low pressure plasma spraying process for wear and corrosion resistance of titanium and titanium alloys, jointly developed by the Research Institute of Chemical Metallurgy of the Chinese Academy of Sciences, Guangzhou Research Institute of Nonferrous Metals and Navy Plant 4801, sprayed wear-resistant and corrosion resistant titanium composite powder coating on the surface of the propeller blades of speedboats with aluminum bronze as the base material, solving the problem of vibration and cavitation resistance of the propeller blades in seawater. The experiment shows that the bonding strength between the coating and the substrate is high, the pollution is small, and the anti vibration cavitation ability is twice that of aluminum bronze. This achievement is currently being tested on naval vessels. If all naval vessels adopt this achievement, it will significantly improve the combat capability of fast boats and can achieve direct economic benefits of millions of yuan.
3. Conclusion
(1) At present, China's shipbuilding industry is developing rapidly and has become the third largest shipbuilding country in the world, but there are still shortcomings in advanced shipbuilding technology. In the face of fierce market competition, it is necessary to minimize production costs, improve production efficiency, and enhance product quality in order to stand invincible in the competitive market.
(2) Powder metallurgy, as a new technology, will undoubtedly play an important role in the future shipbuilding industry. China must fully seize the opportunity of this technological update, strive to develop powder metallurgy technology in the shipbuilding industry, achieve industrial production as soon as possible, and squeeze into the market.
2024 January 3rd Week Marginal Product Recommendation:
Material Specification Sheet–MG-6:
Material specification sheet – MG-6 is Ball and roller bearing steel according to EN ISO 683-17. Ball and roller bearing steel for balls and rollers of any dimension,rings and discs up to 30mm effective thickness.
