Sinter bridges

Bridging sintering, melting, the effect binders, chemical reaction... 

The rough surface of ceramic filter media promotes adsorption of particles and bridging. Sintering of chamotte with a binder results in large blocks from which filter media of any desired shape can be obtained. Using synthetic polymers as binders, ceramic filter media that do not contain plugged pores are obtained. 

Five primary methods exist to form an agglomerated granule. They are formation of solid bridges, sintering, chemical reaction, crystallization, or deposition of colloidal particles. Binding can also be achieved through adhesion and cohesion forces in highly viscous binders. 

Fig. 2.4. Microphotographs of sintered ZnO films with different structures a - structure consists of microcrystals connecting each other by thin crystal bridges b - lace structure is characterized by variety of branch thickness. Magnification 2 1(H.

Semiconductor films of ZnO used as operational elements are obtained by oxidation at - 500 - 600°C in the jet of purified oxygen of zinc film deposited at vacuum iP 10 Torr) on substrates made of fused quartz with subsequent sintering at - 350°C at high vacuum conditions [34]. As it was concluded in paper [17] the sintered polycrystalline sample obtained in such a manner should not be considered as a set of various separate crystallites touching each other but rather as a monolithic pattern in which microcrystals with diameter of 1-10 pm are linked with each other by bridges with length and thickness of the order of 0,1 pm (see Fig. 2.4). 

Thus, the whole complex of existing experimental data indicates that the major part of polycrystalline contacts in vacuum sintered polycrystalline oxides are provided by bridges of open type. Moreover, the vacuum sintering at moderate temperatures 300 - 350°C leads to formation of a unified pattern (see Fig. 2.4, b) which cannot be disjoint into specific microcrystals and connecting bridges [37, 40]. The structure of adsorbents obtained presents a complex intertwining of branches of various thickness. 

Thus, we have considered in detail various theoretical models of effect of adsorption of molecular, atom and radical particles on electric conductivity of semiconductor adsorbents of various crystalline types. Special attention has been paid to sintered and partially reduced oxide adsorbents characterized by the bridge type of intercrystalline contacts with the dominant content of bridges of open type because of wide domain of application of this very type of adsorbents as sensitive elements used in our physical and chemical studies. 

The junction potentials for cells A and B can be assumed to be very similar in magnitude because their liquid junction potentials will be dominated by chloride ions diffusing out from the sinter at the bottom of the SCE (see Figure 3.4), rather than by silver diffusing into the SCE. Cell C has no sinter but a salt bridge. If we therefore consider cells A and B ... 

Bead thermistors are formed by placing two wires, commonly of platinum, in dose proximity and paralld to each other and bridging them with a drop of slurry, which is then sintered into a hard bead and encapsulated in protective glass. Such thermistors are quite stable, approaching, over narrow temperature limits, the stability of industrial metallic thermometers. However, the resistance tolerance may vary from unit to unit by as much as 20%, and matching or interchangeability is usually achieved by selection. Beads can be made quite small, which may allow application in, eg, temperature probes mounted in intravenous needles. 

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