Fabricating products fundamentals

Adequate MW is a fundamental requirement to meet desired properties of plastics. With MW differences of incoming material, the fabricated product performance can be altered. The more the difference, the more dramatic change occurs in the product. Melt flow rate (MFR) tests are used to detect degradation in products. MFR has a reciprocal relationship to melt viscosity. This relationship of MW to MFR is an inverse one as one drops, the other increases or visa-versa. 

Adequate MW is a fundamental requirement to meet desired properties of plastics. With MW differences of incoming material, the fabricated product performance can be altered. The more the difference, the more dramatic change occurs in the product. 

Although hard-templating synthesis provides a simple and versatile pathway to fabricate ID perovskite nanomaterials, the quantity produced in each run is relatively small. Removal of the template through a post-synthesis process may also cause damage to the product. Furthermore, the so-obtained samples are often polycrystalline, which may limit their use in device fabrication and fundamental studies [42]. Therefore, it is highly demanded to develop alterative methods that are effective to synthesize ID perovskite nanomaterials. 

The fundamental goal in the production and appHcation of composite materials is to achieve a performance from the composite that is not available from the separate constituents or from other materials. The concept of improved performance is broad and includes increased strength or reinforcement of one material by the addition of another material. This is the well-known purpose in the alloying of metals and in the incorporation of chopped straw into clay for bricks by the ancient Egyptians and plant fibers into pottery by the Incas and Mayans. These ancient productions of composite materials consisted of reinforcing britde materials with fibrous substances. In both cases the mechanics of the reinforcement was such as to reduce and control the production of cracks in the brittle material during fabrication or drying (2). 

Ceramic boards are currently widely used in high-performance electronic modules as interconnection substrates. They are processed from conventional ceramic precursors and refractory metal precursors and are subsequently fired to the final shape. This is largely an art a much better fundamental understanding of the materials and chemical processes will be required if low-cost, high-yield production is to be realized (see Chapter 5). A good example of ceramic interconnection boards are the multilayer ceramic (MLC) stractures used in large IBM computers (Figure 4.11). These boards measure up to 100 cm in area and contain up to 33 layers. They can interconnect as many as 133 chips. Their fabrication involves hundreds of complex chemical processes that must be precisely controlled. 

Hydrothermal synthesis is a powerful method used for the fabrication of nanophase materials due to the relatively low temperature during synthesis, facile separation of nanopartides in the product, and ready availability of apparatus for such syntheses. Versatile physical and chemical properties of nanomaterials can be obtained with the use of this method that involves various techniques (e.g., control of reaction time, temperature and choice of oxidant and its concentration). Several extensive reviews are available that discuss the fundamental properties and applications of this method [2, 3]. These reviews cover the synthesis of nanomaterials with different pore textures, different types of composition [2, 4—6], and different dimensionalities in terms of morphology [6-8]. 

A small serial production has been set up at the Institute for Instrumental Analysis to develop and demonstrate the fabrication of the microsystem. The production can be subdivided into four phases The wafer-based formation of the fundamental structure, the packaging stage including separation, housing assembly and contact formation of the chips, the deposition of the gradient membrane and the final annealing treatment [4, 5]. 

Other CVD Processes. CVD also finds extensive use in the production of protective coatings (44,45) and in the manufacture of optical fibers (46-48). Whereas the important question in the deposition of protective coatings is analogous to that in microelectronics (i.e., the deposition of a coherent, uniform film), the fabrication of optical fibers by CVD is fundamentally different. This process involves gas-phase nucleation and transport of the aerosol particles to the fiber surface by thermophoresis (49, 50). Heating the deposited particle layer consolidates it into the fiber structure. Often, a thermal plasma is used to enhance the thermophoretic transport of the particles to the fiber walls (48, 51). The gas-phase nucleation is detrimental to other CVD processes in which thin, uniform solid films are desired. 

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