Xiulin Ji

Slurry Erosion Resistance of Laser Clad NiCoCrFeAl3 High-Entropy Alloy Coatings

The slurry erosion resistance of laser-clad NiCoFeCrAl3 high-entropy alloy (HEA) coating was investigated by using a jet erosion testing machine. When the impingement angle increased from 15° to 90°, the volume loss of the HEA coating was accelerated firstly and then followed with a slight deceleration. The largest volume loss of this HEA coating was 4.1 mm3, which was acquired at a 45° impingement angle after a 30-min erosion time with a 15 wt% SiO2 particles (350–600 μm) at an impact velocity of 13 m s−1. Under the same erosion situation, the volume loss of 17-7 PH stainless steel was 5.4 mm3, which means that the HEA coating possesses better erosion resistance under this situation. Annealing treatment is beneficial to improve the erosion resistance of HEA coatings. The 950°C annealed HEA coating had the best erosion resistance because the intermetallic compound Cr3Ni2 was precipitated from the matrix and the volume loss was reduced to 3.5 mm3 at a 45° impingement angle. The worn surface morphologies of HEA coatings were characterized by grooves, ploughing marks, and a small quantity of brittle fractures, which suggests that plastic deformation and abrasive wear were the predominant mechanisms in the slurry erosion of the HEA coatings.

Effect of Heat Treatment on Slurry Erosion Wear Resistance of Amorphous Ni-P Electrodeposits

The slurry erosion wear resistance of heat-treated Ni-P electrodeposits was studied using a jet erosion testing machine. Except at an impact angle of 90°, the erosion wear resistance of Ni-P deposits was improved by heat treatment of air quenching from 400°C. Compared with AISI 304 stainless steel, the heat-treated Ni-P coating has better erosion wear resistance at an impact angle less than 45°. The microstructure of Ni-P deposits was analyzed by X-ray diffraction and the results showed that the relative content of intermetallic compound Ni3P, which was precipitated during heat treatment, is vital to the hardness and the erosion wear resistance. After heat treatment, the primary wear form of Ni-P deposits was not evidently changed and was microcutting and microploughing at 30° and brittle fracture at 90°.

Microstructure evolution and erosion-corrosion resistance of amorphous Ni-P coatings

Amorphous Ni-P coatings with 7.8 wt% P were electrodeposited successfully from an electrolytic bath containing 15 g/L H3PO3. Its microstructure evolution by heat treatment and erosion-corrosion resistance are investigated in this paper. From room temperature to 500 °C, there were three exothermic crystalline phases of Ni5P2, Ni3P and Ni precipitated from the amorphous base. The microstructure evolution of the amorphous Ni-P deposits follows the sequence of amorphous, amorphous-noncrystalline, (Ni5P2 + Ni3P), then (Ni5P2 + Ni3P + Ni) with increasing heat treatment temperature. The mass loss rate of amorphous Ni-P coatings is approximately 14 mg/h and the synergism of erosion-corrosion was larger than half of the total mass loss at an impingement velocity of 8.37 m/s under saline-sand slurry. The erosion-corrosion resistance of amorphous Ni-P coatings can be enhanced obviously by heat treatment because of the elevated hardness and corrosion resistance.

Erosion-Corrosion Behavior of Electrodeposited Amorphous Ni-W-P Coating in Saline-Sand Slurry

The amorphous Ni-W-P coating with 4.8 wt% W and 9.8 wt% P was electrodeposited from the electrolytic bath. Using a slurry pot erosion tester, the erosion-corrosion behavior of this Ni-W-P coating w...

Experimental Study on Dry Electrostatic Cooling in Turning

In recent years, environmental concerns call for the reduced of cutting fluids in metal machining. The green manufacturing techniques are investigated to achieve the objective. In this paper, for the aim of green cutting, the dry electrostatic cooling was applied instead of cutting fluid. The effects of dry electrostatic cooling, compressed air and dry cutting on cutting force, thrust force, cutting temperature, chip formation and tool wear have been examined in turning of AISI1045 steels with carbide tools P10. The experiments were performed at different cutting depths and feeds. The results indicated that the lower cutting force and cutting temperature was gained with applying of dry electrostatic cooling, the values were reduced about 8 percent and 10 percent compared to dry cutting respectively, it is also advantage in forming acceptable chips. In addition, tool wear was decreased in dry electrostatic cooling. The research results show that the production efficiency was increased and clean production was achieved in metal cutting associated with dry electrostatic cooling. Introduction During the metal cutting processes, cutting fluids are used to reduce the negatively effects of heat and friction on both tool and workpiece. The cutting fluids are employed to decrease cutting force and cutting temperature, prevent the formation of built-up edge, generally prolong tool life, enhance the surface finish and remove chip from the cutting area[1]. Unfortunately, there are some harmful chemical composition in conventional cutting fluids, which cause environmental and health problems. On the one hand, the process-generated pollution in machining has been mainly coming from waste cutting fluids because of large-scale application. On the other hand, the disposal of cutting fluids became important environmental and economical problem, due to the cost of dealing with disposal is expensive and increases the production costs. With the development of the societal environmental awareness, regulations and laws, the negatively effects of conventional cutting fluids for environment and health should been considered in metal machining. In the 21th century, the machining technology is desired to be clean, ecological and low energy cost. In recent decades, machining without application of any cutting fluids (dry cutting or green cutting) is becoming more and more popular due to concern of the safety of the environment and health[2]. But there are still some problems about dry cutting in metal machining processes, one of them is the high temperature in cutting zone which negatively affects tool life, especially in the case of dry cutting difficult-to-cut materials. Therefore, the new green cutting technique, which is ecological, economical and superior cooling and lubricating parameters, has become focus in metal machining. In recent years, there are some new green cutting techniques, such as minimum quantity of lubricant[3], spray cooling[4], cryogenic cooling[5], different gas application[6], water vapor[7] and so on. All of them have positively effect of machining process, can decrease the cutting force and cutting temperature, reduce the tool wear and increase the production efficiency. Dry electrostatic cooling (DEC)[8] in machining is one of the new green techniques, which is cheap, clean, no-pollution, eco-friendly and no recovery. The application of dry electrostatic cooling in machining avoids the negatively effects of conventional cutting fluids for environment and health, achieves the aim of green machining. This technique consists of the injection of ionized gas jet with a large number of ions and ozone molecular. Previous studies[8-12] proved the advantages of this 3rd International Conference on Materials Engineering, Manufacturing Technology and Control (ICMEMTC 2016)