Laser-Spark Modification of the Surfaces of Structural Materials by the Example of St3

The paper considers a technology for hardening construction materials using the hybrid (laser-spark) method by the example of steel St3 using hard alloys (VK8, stellite PR-V3K). A significant (several-fold) increase in the wear resistance of the coatings obtained is shown at resistance to abrasive friction due to the good quality of the coating layer and its microhardness (up to 60 GPa). Optimum modes for electrical spark and laser surface modification are proposed. Some physical and chemical properties of the coatings obtained (thickness, roughness, wear resistance, microhardness), as well as their dependence on the hybrid machining modes, are studied. The prospectivity of applying the hybrid (laser-spark) method for hardening of machine parts in order to increase their resistance to abrasive wear during friction is justified.

FROM ACTIVE SHARE TO CUTTING APPARATUS

The subject of the article relates to agricultural machinery, namely, to the working units of root harvesting machines and to cutting device of harvesting machines. In both the first and second designs, work is performed in an abrasive medium, which reduces their service life and increases energy costs. The devices are proposed, in which the work is carried out in the absence of abrasive friction in the working parts. The novelty of devices is marked by patents for invention. The effect is achieved by the special arrangement of the geometric axes of the joints of the links, which are designed on needle roller bearings, by the simplicity of structures, by reduction of energy costs for the drive of the working units, by reliability and durability.

Correlation between Cutting Forces and Tool Wear in High Speed Milling of Graphite

Cutting tools suffer severe abrasive friction and wear in high speed milling of graphite. Cutting forces were measured and analyzed using time-frequency analysis method to reveal the correlation between cutting force variations and tool wear evolution. The static and dynamic force components increased prominently with tool wear. The cutting force Fy was found the most sensitive to the tool wear evolution. The waveform of cutting force became periodic and irregular with the increase of tool wear. Good correlation was found between the first force harmonic and tool wear.

Mechanical properties of single-quasicrystalline AlCuCoSi

The mechanical properties of single-quasicrystals of decagonal AlCoCuSi have been studied for the first time by applying the Vickers indentation method. The hardness has been determined as H ≃ 9.6 MPa. Estimates for the modulus of elasticity and the fracture toughness are given. The quasicrystals are highly strained internally. Scratching experiments show slight anisotropies in the abrasive friction coefficient. The dominant abrasive mechanism is microplowing.