Automatic Spreading Photosensitive Polymer Waveguide Method
In recent years, Boeing subsidiary of HRL laboratory preparation of new materials in the use of 3D printing has made remarkable achievements, developed a technique called the molding technology of photosensitive polymer waveguide method automatically spread the. This is achieved by HRL independent development, can rapid method for mass production of prototype parts, is the United States National Defense Council (DARPA) as part of a light, which lasted 10 years awarded high strength materials in development contract. Depending on the technology, the HRL laboratory has recently prepared ultra light metal materials and ceramic materials.
The basic principle and advantages
Automatic spreading photosensitive polymer waveguide method and stereo lithography (SLA) / digital light processing (DLP) are similar, but not identical, the trick is to make holes in UV penetration lithography mask, exposure to the resin can be cured. At the same time, setting the waveguide until the resin groove bottom, so as to calibrate the light axis. In this method, the ultraviolet radiation will decay, and thus to rely on the inner surface of the resin column and form a continuous downward reflecting optical waveguide, the UV penetration liquid resin through the waveguide effect. The method can create a unique lightweight and high-strength truss structure.
Compared with the traditional 3D printing method, self propagating photosensitive polymer waveguide method to form a solid material is only 30s from ultraviolet radiation to the 3D; and using traditional printing technology, such as ordinary SLA printer to print 25 ~ 50mm high objects, the whole process takes about 4 ~ 8h.
Photosensitive polymer waveguide method can be used for the design and manufacture of automatic transmission structure of different size of microarray, and can obtain different material properties, such as flexibility, elasticity, rigidity and toughness etc..
Different materials with different treatment methods after
Although this method can produce a variety of different types of microarray materials, but there are some difficult problems. The first is the material limited Z axis performance, because ultraviolet rays can penetrate the resin thickness limit, the maximum height of Z axis material is only about 25mm; second is the resin material in the ultraviolet irradiation performance will degenerate.
Preparation of ultra light metal and high temperature ceramic material
Use different processing methods, such as coating or casting, different materials can get the ultimate. For example, nickel aerogel is using electroplating method on the surface of the resin micro lattice structure coated with a layer of thin nickel, made of super light nickel based micro lattice materials. Super light material in the manufacture of this, first by microarray template structure using 3D printing technology, UV direct exposure to light reaction monomer resin, through a small hole, tens of thousands of a mask and a layer of quartz, thus forming a waveguide, can produce 3D microarray structure. After making microarray structure, chemical plating or electroplating metal film laying in micro structure surface, after ablation or chemical etching resin micro structure, obtain the ultra light hollow tubular microarray metal materials. Of course, if you do not have to manufacture metal coating, can also be made of a variety of different microarray structure with other materials, and will have different properties.
The ceramic materials used in engine parts, hot end temperature or extreme environment of the rocket nozzle and nosecones, but it is made by casting or machining of the desired shape is very difficult. In recent years, 3D printing technology makes the production of ceramic pieces may become complex geometry.
However, the traditional 3D printing technology to print ceramic, either photosensitive resin, containing ceramic particles deposited on ceramic particle spray adhesive, or by laser melting ceramic powder bed, will be the production speed limit, and often difficult to avoid the time-consuming binder removal process. Therefore, the current 3D printed ceramic products often appear cracks or uneven material, reliability and strength is low. In addition, most of the current 3D printing ceramic material available only a relatively low melting point oxide ceramics, the high temperature performance of the parts is limited.
Photosensitive polymer waveguide method automatically spread and new polymer resin formula using the HRL laboratory, has verified the rapid preparation of high strength and ability of ceramic parts with complex geometry. This new type of polymer resin by HRL laboratory senior chemical engineer Zak Eckel and Senior Chemist Chaoyin Zhou invention, in the manufacture of ceramic parts, the resin parts with complex shape, and then placed in the furnace for burning, until the resin after pyrolysis, material is uniform shrinkage into high density ceramic parts. The polymer resin can be made of silicon oxycarbide ceramic components have high hardness and strength, high temperature resistance, wear resistance and corrosion resistance.
The manufacturing of ceramic precursor monomer in the polymer resin, HRL laboratory first and using SLA technology to traditional manufacturing complex shape, but takes a few hours or even a few days. For the HRL laboratory using automatic photosensitive polymer waveguide method to spread fast, mass production of resin prototype parts, not only the production speed, but also can produce ultra light ceramic material micro lattice structure. This method can make carbon silicon oxide ceramic parts temperature more than 1700 DEG C, about 10 times the strength of similar to the honeycomb ceramics, and can also manufacture other parts of ceramic materials.
HRL lab said preceramic polymer and polymer derived ceramics research is not just the rise. These materials have been developed as early as 1960s, when it is heated to 1000 DEG C and in argon and other inert gases, the polymer pyrolysis, can form many kinds of ceramic compounds, including silicon carbide, silicon nitride, boron nitride, aluminum nitride, carbon nitride and etc.. At the same time, volatile chemicals such as methane, hydrogen, carbon dioxide, water and hydrocarbons volatilize, namely, shrinkage of ceramic shape dense leaves. In the laboratory of HRL published in the January 1, 2016 issue of the journal "science", "ceramic polymer conversion additive manufacturing experiment report, the research team said in the sintering process of carbon silicon oxide precursor polymer had a weight loss of 42% and 30% linear shrinkage, but the shrinkage" is very uniform, therefore can be predicted, and can according to estimates the size of finished product.
At present, the United States Navy laboratory has been using the ceramic preparation technology to produce micro truss structure, demonstrates a variety of micro structure, honeycomb, honeycomb concave, and exhibit good flexibility.
With the help of new technology, HRL can produce two kinds of practical ceramic products: a microarray structure of large volume weight is very light, can be used to heat board manufacturing aircraft and spacecraft and other external components; the other is a small and complex parts, can be used in the manufacture of electromechanical system, jet or rocket parts.
Application of new materials and new technology
Super light material developed in the laboratory HRL weight of up to 40%, is expected to be used in a new generation of spacecraft. Once HRL has completed further testing, those who are from the MCMA project for small high temperature resistant component rocket and satellite designer is likely to try to use the technology.
The results of microarray materials although recently reported, the actual research of its principle has been carried out in more than a decade ago. The metal structure of microarray is considered likely to become a strong opponent of composite materials in the future, of course, the composite materials can also be made of microarray structure, so that the composite industry there are also opportunities in the face of strong competition at the same time.
Study on silicone precursor polymer ceramic material pyrolysis conversion method, is the focus of high performance ceramic materials research and new growth point. The use of new 3D printing technology, ceramic materials can also be using microarray technology and forming a new complex structure, and the application of high temperature ceramic materials to open up new roads.
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