Choosing the Gravel Composition as a Wear-Resistant Filler in Epoxy Matrix Composites
The wide application of modern composite materials spreads to the production process of machine repair. Recently a number of educational and research organizations have developed new corrosion-resistant composites based on epoxy compounds and silicon dioxide as a dispersed filler. The research carried out by the scientists of the Department of Technical Service showed that a significant increase in the resistance to abrasive wear can be achieved by increasing the diameter of the filler particle. Hence the attention of the researchers was aimed at studying the gravel potential. However, the existence of different groups of this material (granite, quartzite, limestone and slag) makes it necessary to analyze their properties in order to select a group of gravel that can provide maximum abrasive wear resistance. The first criterion for gravel evaluating in terms of its wear resistance is its hardness, since it is known that this mechanical characteristic is related to the abrasive wear resistance in a directly proportional relationship. It is established that granite gravel has the Mohs' hardness from 5 to 7 units. At the same time, the hardness of quartzite and limestone gravel does not exceed 3 units on the same scale. Regarding the slag gravel, it is not possible to speak about hardness because of its considerable porosity. In addition, the strength of granite gravel significantly exceeds the strength of other types of this substance. The grain shape plays a certain role in the level of wear resistance, since it determines the force interaction with the abrasive particle. The most optimal fraction form is a sphere. In the gravel composition there are needle-like particles (35%) and spheroidal ones (65%). Consequently, in terms of providing resistance to abrasive wear granite gravel is preferred over other varieties.