Laminated powder

III. Coated and laminated powders the grains of which are non-homogeneous combinations of the powders above classified. 

Functionally graded SiAION ceramics can be produced by lamination (powder and tape), powder bed, controlling the sintering conditions, infiltration, slip casting and so on. Some of these production techniques will be discussed in the following sections. 

Catalytic curing agents (e g., tertiary amines) Long pot life High heat resistance Can be used as an accelerator or as the sole curative Long elevated-temperature cure Poor moisture resistance Rigid Adhesives Electrical encapsulation Laminates Powder coatings... 

MAJOR APPLICATIONS Printed circuit boards, laminating powder, carbon-fiber composites for aero-engines and military aircraft parts such as flap inboard cover, forward nozzle, gun pack, ammunition pack, blade choke, deep choke, speed brake, and ventral fin/ ... 

Current Patents Curry and curry powder Curry powder Curtain spin process Curtius degradation Curved laminates Curvilinear regression Curvularia falcata Curvularia lunata var. aeri Curvularia trifolii Curzate... 

Fig. 7. Fabrication process for MLC capacitors. Steps are (a) powder (b) slurry preparation (c) tape preparation (d) electroding (e) stacking (f) lamination (g) dicing (h) burnout and firing and (i) termination and lead attachment.

Although it would be desirable to recycle laminate scrap, this has been difficult because of its thermoset nature. However, a 1993 patent (18) suggested a means whereby scrap consisting of cellulose, thermoset resins, and partially reacted resins can be ground to a powder which is used as a filler in a thermoplastic resin. The filled thermoplastic resin is then used for mol ding of various articles. 

This includes wire enamels on a base of polyvinyl formal, polyurethane or epoxy resins as well as moulding powder plastics on phenol-formaldehyde and similar binders, with cellulose fillers, laminated plastics on paper and cotton cloth base, triacetate cellulose films, films and fibres of polyethylene terephthalate. 

The thermosetting materials are said to be initially linear but are cross-linked by heating in air to a temperature of at least 345°C. It is claimed that they have a useful working range up to 315°C. The materials may be used in compression mouldings powders, as the binder resin in glass cloth laminates and as the polymer base in heat-resistant metal coatings. 

In addition to their use in moulding powders and laminates, melamine-formaldehyde resins are widely used in many forms. 

At one time thiourea-urea-formaldehyde resins were of importance for moulding powders and laminating resins because of their improved water resistance. They have now been almost completely superseded by melamine-formaldehyde resins with their superior water resistance. It is, however, understood that a small amount of thiourea-containing resin is still used in the manufacture of decorative laminates. 

At about the same time, an allyl resin known as CR39 was introdueed in the United States as a low-pressure laminating resin. This was followed in about 1946 with the introduction of unsaturated polyester laminating resins which are today of great importance in the manufaeture of glass-reinforced plasties. Alkyd moulding powders were introduced in 1948 and have since found specialised applications as electrical insulators. 

The dough moulding compounds were originally developed in an attempt to combine the mechanical properties of polyester-glass laminates with the speed of cure of conventional moulding powder. In spite of their somewhat high cost they have now established themselves in a number of applications where a mechanieally strong electrical insulant is required. 

This monomer has been used as the basis of a laminating resin and as a reactive diluent in polyester laminating resins, but at the present time its principal value is in moulding compositions. It is possible to heat the monomer under carefully controlled conditions to give a soluble and stable partial polymer in the form of a white powder. The powder may then be blended with fillers, peroxide catalysts and other ingredients in the same manner as the polyester alkyds to form a moulding powder. Similar materials may be obtained from diallyl isophthalate. 

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