Post Buying Request

Influence of Graphite Mould on the Quality of Diamond Segments

This article introduces the influence of graphite mould on the quality of diamond segments.

From: iAbrasive.comDate: 2015-07-06 09:37:28Views: 519

In the hot-pressing sintering process of synthetic diamond segments, the graphite mould plays the dual roles of the heating element and the supporting mould. The quality of graphite mould and the performance parameters of graphite directly affect the exterior shape and size precision of the synthetic diamond segments, the binder content in the segment, the hardness of substrate material, the bending strength, and the cutting performance and service life of the segments.

A. The influence of volume density of graphite , shore hardness, flexural and compressive strength

When the graphite plays the mold supporting role in the process of hot-pressing sintering process, it requires higher volume density of graphite, shore hardness, flexural and compressive strength. The higher the better! Its bulk density should be greater than 1.75 g/cm3. As the mould indenter, its bending strength is more important. If the volume density of graphite is low, its hardness, flexural and compressive strength will also become lower, and easy to fracture or break in use.

B. The influence of open porosity of graphite

In order to guarantee the finish of segments, it also requires fine particle structure of graphite, and the open porosity should be less than 13% as small as possible, in addition to higher surface finish for graphite mould.

If mould graphite has low volume density and high porosity, graphite will absorb more metal bond from segments in the process of hot-pressing sintering process, impregnating from metal to graphite, and increase the weightlessness rate of the segments, which will change the matching ratio between metal bond and diamond in the segments, lowering the binder holding ability for diamond. Even the adhesion between the surface of segments and graphite mould will be produced, and lower the surface finish of the segments.

C. The influence of impurity content in the graphite

As a hot-pressing sintering graphite mould, it needs lower ash content and higher graphitization as far as possible. If the impurity content in the graphite is too high and the ash content is too big, the extra impurity in the graphite mould will react with the metal bond of the segments in the process of hot-pressing sintering process, adhere to the surface of diamond segments, and produce the dark red trace, and finally affect the appearance of the diamond segments.

D. The influence of graphite resistivity

When the graphite mould as the electric heating element of synthetic diamond segments in the hot-pressing sintering process, it needs the resistivity is consistent between the pressure head and graphite blocks, with high homogeneity. If the resistivity is different between graphite blocks, according to the joule Lenz's law, it will lead to the different calorific value and higher temperature difference. In the hot-pressing sintering process of diamond segments, the temperature can lead to the differences in the hardness and bending strength of substrate materials, which affect the abrasion ratio and cutting ability of segments.

 

share:

Top News

Sponsored links