Product performance based on contact-condensing binders as a function of pressing parameters
The mechanism of contact-condensation solidification provides the formation of a solid rocky body in the event of contact between the microparticles of a substance of amorphous or unstable crystalline structure without changing its chemical composition as a result of physical surface phenomena. Therefore, to provide stronger contacts between the particles of such binders during their condensation, it is necessary to apply external pressure (compression).
The implementation of such binders is not linked to the timing of grieving. The curing process is carried out immediately at the time of contact between the particles of such binders. In the future, the strength of artificial stone increases in natural conditions and in water.
The results of studies of the dependence of the pressing parameters on the basic performance of the products based on the binder contact-condensation hardening are presented. It is established that in order to maximize the effective action of pressures, which provide plastic deformation during compaction and provide the most dense packing of powder particles, there is a limit of working pressures in the range from 40 to 150 MPa. It is shown that it is convenient to use mathematical expressions (extrusion equations) when analyzing the processes occurring during extrusion, which reveal a functional relationship between the pressure and the density of the material thus obtained. With the help of the equations of pressing, for each powder or group related to the physicochemical parameters of the powders, the most economical parameters of the pressing modes can be determined.
The data obtained for the compression pressure characterizing the action of plastic deformation for the test mixtures is in the pressure range from 32 MPa to 158 MPa. Increasing the pressure above leads to the transition of plastic deformation into elastic deformation, in which the seal passes due to the destruction of particles under the action of high pressures.
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