Composite graphite platelets

To achieve the goal of required performance, durability, and cost of plate materials, one approach is improvement of the control of the composition and microstructure of materials, particularly the composite, in the material designing and manufacturing process. For example, in the direction of development of thermoplastics-based composite plate, CEA (Le Ripault Center) and Atofina (Total Group) have jointly worked on an irmovative "microcomposite" material [33]. The small powders of the graphite platelet filler and the PVDF matrix were mixed homogeneously by the dispersion method. The filler and matrix had a certain ratio at the microlevel in the powder according to the optimized properties requirements. The microcomposite powders were thermocompressed into the composite plate. 

The details of the structural characteristics of individual constituents in the various carbon deposits were obtained by examination of a number of specimens from each experiment in a JEOL 100 CX transmission electron microscope that was fitted with a high resolution pole piece, capable of 0.18 nm lattice resolution. Suitable transmission specimens were prepared by applying a drop of an ultrasonic dispersion of the deposit in iso-butanol to a carbon support film. In many cases the solid carbon product was found to consist entirely of filamentous structures. Variations in the width of the filaments as a function of both catalyst composition and growth conditions were determined from the measurements of over 300 such structures in each specimen. In certain samples evidence was found for the existence of another type of ca naceous solid, a shell-like deposit in which metal particles appeared to be encapsulated by graphitic platelet structures. Selected area electron diffraction studies were performed to ascertain the overall crystalline order of the carbon filaments and the shell-like materials produced from the various catalyst systems. 

Coatings may be metal based such as gold, TiN, CrN, metal carbides, etc. carbon-based such as diamond-like carbon, graphite, graphite platelets, carbon-resin composites, conductive tin oxides, etc. Coatings have to be compatible with the substrate bare metal and have good adhesion and peel resistance. 

Figure 5.28. Composites with platelet-shaped graphite filler particles that are poorly bonded to the polymer matrix have broad Tg regions (U) when the filler is treated with a coupling agent to create stronger adhesion, the glass transition damping peak narrows and the loss peak temperature decreases (T) (from Chartoff, 1986, with permission of de Gruyter).

Yasmin A, Daniel IM (2004) Mechanical and thermal properties of graphite platelet/epoxy composites. Polymer 45 8211... 

Borosilicate glass matrix composites with chopped graphite fibres are highly machine-able materials [29]. Machinable glass-ceramics containing interlocking platelet-like and... 

Clay platelets can serve as inorganic polyanions. Hb retained its native conformation in films made by casting aqueous dispersions of the protein and a DDAB-clay composite [63], Cyclic voltammetry of Hb-DDAB-clay films on pyrolytic graphite (PG) electrodes showed a pair of well-defined and nearly reversible peaks at a midpoint potential of about -0.06 V vs. NHE at pH 7. Only the inner layers of the film closest to the electrode were electrochemically active. These films had excellent stability over several months storage. Hb in these films is not located completely between the clay platelets. 

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