Introduction: Metal is currently one of the most popular materials in additive manufacturing processes. Its excellent properties are suitable for use in areas where performance and strength requirements are most demanding. In this article we will focus on 3D The two main metals used in printing: titanium and aluminum. These two materials are mainly used in laser powder bed fusion(L-PBF) or directed energy deposition(DED) For other processes, the material is generally in powder form. We will compare their similarities and differences to better understand their properties and applications, as well as the benefits they bring in the manufacturing process.
Production and properties of titanium and aluminum
titanium
Titanium is a material that does not exist as a distinct element in nature and must be obtained from rutile. (TiO2) or ilmenite (FeTiO3) Extracted from other minerals. The extraction of pure titanium is a complex process involving several steps. The most widely used method for producing pure titanium isKrollmethod, by the American chemist WilliamJ.·Kroll1940years of development. This method uses chlorine gas (Cl2) reduced titanium dioxide (TiO2) to produce titanium tetrachloride ( TiCl4)then use magnesium (Mg) reduction. Although Kroll The method is effective for producing pure titanium, but it is an expensive process that requires large amounts of energy. Additionally, the high reactivity of titanium makes it difficult to obtain as a pure metal with a purity of99.9% The sample is considered to be commercially pure titanium. This is why it is often combined with other elements to form alloys.
Titanium has many properties and can therefore be used in many areas. It is usually used in alloy form, but pure mined titanium is often used in the medical industry due to its high biocompatibility. Its main characteristics are high mechanical strength, low density, excellent corrosion resistance and high rigidity.
used for3DThe main types of printed titanium alloys are:
●Ti6Al-4V,5 Quality: The largest and most common titanium alloy. It is used in additive manufacturing due to its high strength and durability. The alloy is made of titanium, aluminum and vanadium and can withstand high temperatures and corrosive environments.
●Ti6Al-4V,23 Grade: Commonly used in medical implants and prosthetics due to its biocompatibility.
●Ti Beta 21S: Stronger than traditional titanium alloys and more resistant to oxidation and deformation. It is ideal for orthopedic implants and aerospace engine applications.Beta Titanium is very popular in orthodontics.
●Cp-Ti(pure titanium),1 class,2 Quality: Due to the biocompatibility of titanium with the human body, this alloy has a wide range of applications in the medical industry.
●TA15: An alloy composed almost entirely of titanium to which aluminum and zirconium have been added. Parts made from this alloy are very strong and resistant to high temperatures, making them ideal for making strong components for aircraft and engines. They are also very light in relation to their strength.
aluminum
Aluminum is a metal that offers an excellent compromise between lightness and strength. In addition to being corrosion resistant, it can also be welded. Its pure form is very rare, which is why it is used in the form of alloys containing metals such as silicon and magnesium which improve its physical and mechanical properties. To obtain pure aluminum, you must first useBayer Alumina is obtained from bauxite. The ore is washed and crushed, dissolved in caustic soda and filtered to obtain pure aluminum hydroxide. It is then heated to obtain alumina powder. then use Hall-Héroult Process for the electrolytic reduction of aluminum oxide to obtain pure aluminum.
As mentioned above, aluminum alloys are more common than pure aluminum and are used in many industrial applications. In addition, they have a very good strength/weight ratio and very good resistance to fatigue and corrosion. They are also recyclable, thermally and electrically conductive and have low toxicity.
for aluminum3DThe main alloys printed are as follows:
●AlSi10Mg: This is the most common alloy formed from silicon and magnesium. It can be used to create strong, complex parts and is used to make crankcases, engine parts and production tools.
●Al2139: The strongest aluminum alloy, ideal for industries such as automotive due to its lightness, strength and chemical resistance. It was used by the United States Air Force, Mercedes–Used by organizations such as Mercedes Benz and Airbus. The beauty of this material is that it is designed for additive manufacturing and outperforms many other alloys on the market.
●Al7000Series: This is a well-known series of high tensile strength and low temperature powder alloys.
●Al6061 and Al7075:recently,3D Manufacturers use both alloys with excellent results.6061 The tensile strength and hardness are less than 7075. on the other hand,7075 Has a report 6061 Aluminum has better impact resistance and less deformation.
●A201.1: It is 200 Part of a series of copper-aluminum alloys known to be very strong. However, they are difficult to cast. These alloys are recommended for applications where the strength-to-weight ratio is critical, such as transportation and aerospace.
What is the difference between the two?
In terms of strength to weight ratio, titanium is ideal where high strength and robustness are required, which is why it is used in medical components and even satellite components. On the other hand, although aluminum is not as strong as titanium, it is lighter and more affordable. In terms of thermal properties, aluminum is well suited to applications requiring high thermal conductivity. Titanium, on the other hand, is well suited for applications in high temperature environments, such as aerospace engine components, due to its high melting point. Aluminum and titanium have excellent corrosion resistance. However, titanium is more biocompatible than aluminum, which is why it is widely used in the medical field.
material form and 3D Printing technology compatibility
form
In most cases, titanium and aluminum come in powder form, but they are also available in wire form, e.g. Virtual Foundry Or Nanoe Delivered with titanium or aluminum wire. use these metals 3D To print a part, you must first obtain alloy powder, which is mainly done using two techniques: plasma atomization or gas atomization. Plasma (ionized gas) atomization is a process that uses high temperatures, energy and heat sources, inert media (such as argon), and high speeds to atomize metal. This process produces high quality, wear-resistant powders. Gas atomization, on the other hand, uses air, argon, or helium as gas to interrupt the flow of molten material. This is a highly efficient and widely used process to produce fine spherical metal powders.
used 3Dprinting technology
be in 3D Titanium is used in printing and processes that can be used include laser powder bed fusion. (L-PBF)、DED and adhesive jet (BJ). For processes related to aluminum, in addition to those already mentioned, there is also cold spraying.
exist L-PBF a laser beam is used to heat layer by layer of metal powder to its melting point and build the object. Titanium at very high temperature (1,600°C) bottom under the 3D Analyze the thermal and mechanical effects of materials before printing. Aluminum has a much lower melting temperature (approx. 630°C), but aluminum has high reflectivity and thermal conductivity. Another interesting aspect of additive manufacturing of aluminum is that it forms a natural oxide layer.
about DEDit is very similar to the previous process, but here the material is melted as it is deposited in the nozzle and can be used in manufacturing in powder or wire form. Typically, this technology results in higher production speeds and lower costs per unit volume.
existBJAs part of the process, the material is in unmelted powder form, but in order to make the particles adhere to each other, multi-nozzle printing is used to spray the adhesive onto the layer in specific locations. A sintering step or other post-curing treatment is also required after printing. when they leave 3D Once printed, these parts are very fragile and porous and require heat treatment to achieve the final mechanical properties.
In the cold spraying process, metallic materials are also present in powder form, but since they do not need to be melted or melted in this case, cold spraying avoids thermal deformation and does not require d protective atmosphere.
post-processing
For best results, one or more post-processing steps are required. There are no specific differences in post-processing for titanium and aluminum, so the following steps apply to both materials. Since titanium and aluminum are often used in applications subject to mechanical stress, shot peening is very useful. Small balls of metal or ceramic are projected onto the surface of the part, causing a controlled deformation of the surface layer of the part. This improves the adhesion of subsequent coatings and reduces, among other things, the risk of cracks and breaks. Shot blasting removes only the top layer of material, improving the aesthetics of the part, removing dirt and corrosion, and preparing the surface for subsequent coatings.
Another option is to combine metal printing with traditional manufacturing methods.CNC Machining is a post-processing process suitable for this purpose as it ensures tight tolerances and the required surface finish. Especially using DED technology,3D The surface of the printed part is very rough because the metal melts directly during the ejection process. It is therefore always necessary CNC Treated to obtain a smooth and defined surface.
Annealing is a heat treatment option in which printed parts are heated to high temperatures and cooled rapidly to change the microstructure, thereby increasing the material’s ductility, or ability to deform under load before breaking. Generally, this process achieves better mechanical properties and is mainly used for aluminum parts.
When aluminum and titanium are used in a so-called indirect way 3D printing process (eg. FDM or powder bonding), sintering is also necessary. After the printing stage, the part must go through a debinding process to separate the polymer from the metal binder. The parts are then heated in a sintering furnace to a precise temperature, just below the melting temperature, which solidifies the final object. This results in a part with very low porosity because the cavities where the adhesive is located are compressed during the process, causing the part to shrink.
application
The aerospace industry is seeing significant benefits from additive manufacturing using titanium. It is an ideal material for making aerospace components such as jet engines and gas turbines because it can significantly reduce the weight of highly stressed structures. An example of the use of titanium in additive manufacturing is Boeing’s partnership with Norwegian Titanium Cooperate for 787 Dreamliner manufactures large structural components. The technology used in this process is DEDwhich would be faster than powder-based systems 50 arrive 100 times and uses less titanium than forging 25% arrive 50%potential savings per plane of up to 300 million dollars.
Although titanium is currently passing 3D Printing is used for space exploration, but the use of aluminum in industry has increased. For example, Boeing produces aluminum alloys coated with nanoparticles during the cooling phase. 3D Print parts. This allows extremely strong aluminum alloys to be welded without cracking at high temperatures. The manufactured parts are lighter, allowing the aircraft to use fuel efficiently and travel longer distances on the same amount of fuel.
Although the high price of titanium in the automotive sector may hamper its widespread use, we could see an increase in its use in this area, particularly in the luxury segment. at present,3D Print for manufacturing weight/Components where performance ratio is critical. For example, Bugatti uses GDT The technology only uses 45 The brake calipers for its titanium braking system were printed in just a few hours. The result would be lighter than conventional milled aluminum brake calipers. 40%. Despite its low weight, the titanium components also ensure its elasticity and temperature resistance.
Aluminum, on the other hand, is more common in the automotive industry. Used by Porsche 3D Print as a flagship product 911 car model GT2RS Manufacturing of high performance aluminum pistons. Thanks to this technology,700 The twin-turbo engine can reach 30 improved power and efficiency. Moreover, in 2020 In 2017, Porsche produced an all-aluminum drivetrain for its electric drivetrain 3D Print the case that passes all of the company’s quality and load tests.
Finally, titanium is a very attractive material in the medical industry due to its high strength and corrosion resistance, as well as its biocompatibility, making it ideal for orthopedic and dental implants.3D Printing allows for the creation of porous structures that mimic the texture of bone, facilitating rapid healing and growth of bone and tissue. Turkish TrabTech Titanium is used to create trabecular implants such as hip joints. Aluminum is less common than titanium in the medical industry, but is used in orthopedic and dental applications.
source:3dnatives
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