Key Engineering Materials Vol. 642

Abstract: This work aims at investigating the electrical property and the friction force of Ga-In-Sn eutectic alloys. The performance of the alloys is increasingly needed on conducting lubricant. Resistance force dependence of normal force was examined by atomic force microscopy, and the results showed that Ga₆₅In₂₁Sn₁₄ had the highest friction coefficient of 3.07 and Ga₈₀In₁₃Sn₇ had a lowest friction coefficient of 1.46. Electrical resistivity of the studied eutectic alloy was from 25.9 to 27.7 μΩcm at 25°C. Accordingly, the electrical resistivity as a function of temperature revealed a temperature coefficient of ranging from 12.67 ✕10^-3 °C^-1 to 4.94 ✕10^-3 °C^-1. High thermally stable and wetting capability make the studied Ga-In-Sn alloys can potentially be used as a conducting lubricant.

Abstract: Mass amount of equipment and harsh operating condition in steel plants require comprehensive management system, along with lubrication techniques such as lubricating oil quality improvement, used oil monitoring, etc., to ensure proper tribological condition for all mechanical components. In that case, cost management is essential to evaluate the performance of tribology management. This paper is intended to discuss the system establishment, scope of work and actual applications of tribology management in China Steel.

Abstract: Nowadays environmental awareness issue draws the attention of the scientists; lubricant industry also focuses on environment friendly lubricating oils. Therefore, vegetable oils draw the attention of scientists because of environmental friendly as well as good lubricating characteristics. However, good lubricating vegetable oils often shows inferior property because of low thermal stability, hence, to enhance the performance of vegetable oils self-lubricating diamond like carbon coating is considered, which helps in lowering the friction force which in turn lower friction induced heating, as a result stability of vegetable oils increases. In this current research, three vegetable based oils (sunflower, palm, coconut) are considered as lubricating oil. Tribological tests are conducted by ball on plate tribo-testing machine, tetrahedral type diamond like carbon coated plates and uncoated balls are used in the tribo-pair. Among the testing conditions sunflower oil shows good friction and wear characteristics and coconut oil shows inferior friction and wear characteristics.

Abstract: Currently diamond like carbon (DLC) coatings application for automotive components is becoming a favorable strategy to cope with new challenges faced by automotive industries. DLC coating is very effective to lower the coefficient of friction and wear rate, which in turn could improve fuel efficiency and durability of the engine components. Commercially available fully formulated lubricating oils are specially produced to enhance the lubrication of ferrous materials. Therefore, nonferrous coating (DLC) interaction with commercial lubricating oil needs to be investigated. In this current investigation, coefficient of friction and wear rate were investigated by ball on plate tribo testing machine at different temperatures in the presence of SAE 40 lubricating oil. At high test temperature coefficient of friction decreases, however wear rate increases for the a-C:H coated plate, however, steel/steel contact shows opposite trend of coefficient of friction and wear rate change.

Abstract: W_(100-x)%C_x% coatings with different tungsten and carbon contents were deposited by unbalanced magnetron sputtering. The microstructures and mechanical properties of the W_(100-x)%C _x% coatings was characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), nanoindentation and adhesion testing techniques. The tribological performance of the coatings was investigated using a pin-on-disc trobometer under dry conditions. Experimental results indicated that coating microstructure, mechanical properties and wear resistance varied according to the tungsten and carbon contents of the coatings. The W_72%C_28% coating had the highest hardness/elastic modulus (H/E) ratio. In the ball-on-disc wear tests, it was found that the W_72%C_28% coating exhibited the best wear resistance.

Abstract: Within past 20 years, high surface qualities of cold strip were demanded by automotive industry and electrical engineering. Main purposes of cold rolling processed are to provide high quality surface and generate appropriate roughness for different customs. Emulsion is a common coolant used in cold rolling processes, Properties of base oil in emulsion, concentration, roughness of work roll, rolling speed and reduction are important parameters, which dominate the surface qualities of cold rolled strip. Hence, a powerful cold rolling model which can describe complicate tribological behavior in roll bite is required. In this article, a cold rolling model which integrates roll deformation and mixed lubrication in inlet zone and biting area was developed. The thickness of oil film, fraction of contact area and coefficient of friction in roll bite are calculated.

Abstract: With the rising of public environmental awareness and energy saving goal, high efficient transmission of ballscrew is widely used for production equipment. Of all the ballscrew application, heavy loading is the most stringent operation condition. The crucial techniques for this application are ball recirculation system and lubrication design. In this article, a heavy-load type ballscrew is verified to meet the application requirements through experiments, dynamic simulations and test runs on test bench.

Abstract: This study investigated the removal improvement of micro burrs of aluminum alloy materials using vibrated abrasive grinding machining. The image processing technology is used to examine and quantify the micro-hole burr profiles. The experimental results show that the micro burr was uniformly removed as the workpiece is fixture with vertical direction. In addition, the burr removal improvements are effectively influenced by the flowing velocity and the vibration energy of abrasive particles. The flowing velocities are dependent on the size and gravity of the abrasives and the vibration energy is determined by the material properties and the hardness of the abrasives.

Abstract: This study aims to develop a polishing process improvement technology for deep micro-hole knockout hole wall with high aspect ratio, and discuss the optimal polishing parameter combination of abrasive jet machining method and micro-elastic abrasive particles for deep micro-hole knockout hole wall surface. A micro-elastic abrasive process technology was thus developed. The experimental results showed that the micro-elastic abrasive has better grinding effect on the surface roughness of knockout hole wall in length of 300 mm and in inside diameter of ψ2mm in the machining conditions of jet pressure 0.5MPa, volume mixing ratio 2:1 of abrasive particles to additive and vacuum attraction 70 cmHg. It was improved from 2.39 μm Ra (10.74 μm Rmax) to 0.08 μmRa (1.12 μm Rmax), proving the feasibility of micro-elastic abrasive. The surface was improved well, and the process time was shortened greatly.

Abstract: Ball screw is a high-precision and high performance linear drive of mechanical elements. The frictional heat of internal components what is very significant impact for platform transmission in high speed and the high axial load and causes the thermal expansion of element. In this research , the influence of different greases on ball screw is investigated in thermal rising of nut and driving torque in high speed and high axial load. A vertical motion platform was used for driving performance test. Thermal rising of nut of ball screw and the variance of transmission torque whose lubricated by high viscosity base oil grease is significant larger than the lower one. High viscosity grease is not easy to carry out the friction heat generated at ball and raceway contact area due to the bad flowing properties. It also has more serious wear occurred at contact area and high friction force, whose causes the large variance of transmission torque.