Generation of equipment generation of materials
Metal matrix composites (MMCs) have been widely used in various advanced industries because of their high modulus and strength, good wear resistance and corrosion resistance. With the upgrading of equipment, additive manufacturing (AM) technology as a method to manufacture MMC has attracted people's attention and application.
Compared to conventionally manufactured MMCS, AM-produced MMCS exhibit a more evenly distributed enhancement and finer microstructure, resulting in similar or even better mechanical properties. In addition, AM technology can produce large pieces of MMC with extremely low porosity, and can manufacture geometrically complex MMC components and MMC lattice structures.
Delwyman has always been concerned about the development of binder jet 3D printing for the preparation of metal matrix composites, and has cooperated with a number of national key research laboratories to successfully validate the binder jet additive manufacturing applications of a variety of metal matrix composites, including 316 impregnated copper, 420 impregnated copper, tungsten copper alloy and tungsten impregnated Invar alloy. In addition, experiments have also been carried out on ceramic matrix composites, such as boron carbide aluminizing, silicon carbide aluminizing and graphite siliconizing.
Binder jet printing
BJ process is to inkjet print the liquid adhesive according to the 2-D profile divided by software, and use the layer by layer deposition of the adhesive to produce the physical object. BJ printing can use any powdered raw material (such as metals, ceramics, polymers and composites) in combination with adhesives to produce components, in addition, BJ printing can be carried out in an unprotected atmosphere, making it a cost-effective and high-speed additive manufacturing process compared to other methods.
In the BJ process, the absence of heat sources precludes the possibility of in-situ reactions in the printing process, and in most cases, the reinforcement material needs to be pre-integrated into the feedstock. Due to the characteristics of BJ process, the pre-alloyed powder is more conducive to the preparation of MMC with excellent properties.
MMCs Additive Manufacturing
Aluminum Matrix Composites (AMC)
AMCs exhibit properties derived from aluminum alloys and reinforcement, allowing AMCs to exhibit high specific strength and stiffness, low CTE, and good wear resistance. As a result, AMC has become a lightweight material commonly used in various industrial sectors. Traditional AMCs can be produced by melt processing or powder metallurgy. Despite the promising performance of traditional AMCs, they have been observed to exhibit some limitations, including irregular distribution of reinforcement, inadequate interface bonding between matrix and reinforcement, and high porosity. Recently, additive manufacturing techniques have been used to manufacture particulate reinforced AMCs that can overcome these problems. Compared with traditional AMCs, AMCs produced by AMC have relatively uniform reinforcement layer distribution, low porosity and clear matrix-reinforcement interface. The most commonly used reinforcement materials in AMC include SiC, TiC, AlN, BN, Si3N4, Al2 O3, ZrO2, and TiO2.
Titanium Matrix Composites (TMC)
TMC is a composite material made of titanium alloy and reinforced material. TMC is known for its high hardness, strength and high temperature resistance. They may be used as a replacement for titanium alloys in aerospace, chemical engineering, surgical implants and Marine applications. TMC produced using traditional methods can be classified as continuously enhanced TMC or discontinuously enhanced TMC. However, continuous reinforced materials such as carbon fiber and silicon carbide fiber are vulnerable to damage from heat sources such as lasers and electron beams. Therefore, the TMCs produced by additive manufacturing are mainly discontinuous enhanced TMCs, such as particle enhanced TMCs. High-modulus and high-strength carbides, silicides, oxides, and borides such as TiC, SiC, Y2 O3, TiB, TiN, and Ti5 Si3 are commonly used as enhancers for TMCs.
Nickel Matrix Composites (NMCs)
Ni and Ni alloys are widely used in turbines and petrochemical plants to make hard reinforcement materials from nickel substrates, which are very promising in high-temperature structural materials. Many nickel alloys have been successfully produced by additive manufacturing methods, such as Inconel 625, Inconel 718, and Ni-based superalloys. Therefore, the preparation of NMCs by AM method has aroused great interest of researchers. Both PBF and DED methods can prepare NMCs. Various reinforcement materials, such as CNT, TiC, WC, and SiC, have been used in additive manufacturing NMCs by addition or in situ synthesis.
Iron Matrix Composites (IMC)
IMCs has high strength, stiffness, modulus, wear resistance, fatigue resistance and corrosion resistance, so it has been widely recognized in modern industry. IMCs produced using traditional techniques (such as penetrant casting and powder metallurgy) usually have poor wettability between the matrix and the reinforcing material, resulting in high residual stress, low density, poor strength, high crack susceptibility, and reduced mechanical properties. Significant efforts have been made to address these issues using additive manufacturing techniques.
Other
Binder jet 3D printing technology can also develop other MMCS, copper composites and cobalt-based composites. Many reports can also be found on copper matrix combinations. In recent decades, copper matrix composites have received a lot of attention due to their good mechanical properties and high electrical/thermal conductivity, making them ideal for lightweight macroscopic conductors in electronics.
Summary
In the future, two important research directions of additive manufacturing MMCs should be highly valued. One is to optimize the cost of additive manufacturing technology. Another is the potential application of MMC for additive manufacturing production. The economics of manufacturing MMCs by additive often exceed those of conventional methods.
Combining the benefits of additive manufacturing technologies, such as design freedom, material savings, topologically optimized design, rapid prototyping, custom production and reduced assembly, with the benefits of MMC, such as improved strength and stiffness, reduced component weight, improved wear and corrosion resistance, improved thermal performance and improved fatigue life, MMC produced by additive manufacturing has considerable application prospects in many industrial sectors.
Additive manufacturing techniques have successfully produced high-performance MMCS such as Ti, Al, Fe, and Ni-based MMCS. The addition of reinforcing materials to MMC improves its microstructure and prevents the initiation and propagation of cracks, thereby improving mechanical properties compared to pure metal substrates. The rapid cooling rate in the additive manufacturing process further refines the microstructure of the MMC. Therefore, the resulting MMC produced by additive manufacturing has the advantages of both additive manufacturing technology and reinforcement materials.