Antioxidant behavior and tribological performance of a novel multifunctional additive in complex lithium grease

Purpose This paper aims to contrastively investigate the antioxidant behavior and tribological performance of a novel multifunctional additive (PBT) and dialkyldithiophosphate (ZDDP) in complex lithium grease (CLG). Design/methodology/approach PBT was successfully synthesized through esterification reaction. The antioxidant behavior of PBT and ZDDP was investigated by thermal analysis, and meanwhile, their tribological performance was evaluated by Optimol SRV-IV oscillating reciprocating friction and wear tester (SRV-IV test) and MRS-1J four-ball tester (Four-ball test). Furthermore, their anticorrosion ability was determined by copper strip corrosion test. Findings Four-ball tests showed that the extreme pressure property of PBT was a little inferior to that of ZDDP. Besides, all the other results demonstrated that PBT showed more superior antioxidation stability, friction-reduction and antiwear ability, as well as anticorrosion performance than ZDDP. Originality/value This work provides a study of hindered phenol derivative as a multifunctional additive in lubricant grease, which can contribute to the development of substitution of ZDDP.

Modulation of Lithium Disilicate Translucency through Heat Treatment

The aim of this study was to present a control method for modulating the translucency of lithium disilicate ceramics through thermal refinement. Identical lithium disilicate blocks were thermally refined using four different heat treatment schedules, and the microstructure, translucency, and flexural strength of the ceramics were investigated in detail by SEM, spectroscopy, and a piston-on-three-ball test. The results showed that ceramics treated under higher heat had larger grains, with an average size between 240 and 1080 nm. In addition, a higher transmittance of all wavelengths was observed in ceramics treated under lower heat, and the transmittance in the 550 nm wavelength ranged from 27 to 34%. The results suggest that the translucency of ceramics can be modified through thermal refinement under two conditions: (1) the particle size of the ceramic is small enough to achieve minimal grain-boundary light scattering, and (2) the percentage of particles allowing visible light transmission is altered by the heat treatment.

A New Benzotriazole Phosphite Ammonium Salt Derivative (PN) Extreme Pressure Additive to Improve Gear Oil Tribological Properties

In this paper, a new benzotriazole phosphite ammonium salt derivative extreme pressure additive called PN was synthesized. Four-ball experiments and SRV experiments were used to test the high temperature and extreme pressure performance of PN additive, and comparisons were made with the commonly used additives including ZDDP and T304. The results show that the COF and wear amount of the PN additive in the four-ball experiment were much smaller than that of the ZDDP and T304 additives. The COF of the PN additive in the RSV experiment changed slightly with temperature, and it had better high temperature extreme pressure performance in friction reduction than the traditional ZDDP and T304 additives. When the temperature was 120oC, the COF of PN was about 30% lower than that of traditional additives. Thermogravimetric analysis showed that the failure temperature of PN additives was within 180-200oC, and the thermal stability was better than that of ZDDP and T304. After the four-ball test, SEM was used to observe the morphology of wear spots on the ball surface. It was found that the wear spots containing PN additive had slight adhesive wear, while those containing ZDDP and T304 showed serious adhesion and ploughing wear, and the surface appeared peeling and tearing. XPS was used to detect the chemical composition of friction surface containing PN additive, and thus the formation process of film on frictional surface was analyzed.

Development of new 9-ball test protocols for assessing expertise in cue sports

Background This study aimed to develop new test protocols for evaluating 9-ball expertise levels in cue sports players. Methods Thirty-one male 9-ball players at different playing levels were recruited (recreational group, n = 8; university team, n = 15; national team, n = 8). A 15-ball test was administered to indicate overall performance by counting the number of balls potted. Five skill tests (power control, cue alignment, angle, back spin, and top spin) were conducted to evaluate specific techniques by calculating error distances from pre-set targets using 2D video analysis. Results Intra-class correlation analyses revealed excellent intra-rater and inter-rater reliability in four out of five skill tests (ICC > 0.95). Significant between-group differences were found in 15-ball test performance (p < 0.001) and absolute error distances in the angle (p < 0.001), back spin (p = 0.006), and top spin tests (p = 0.045), with the recreational group performing worst while the national team performing best. Greater inter-trial variability was observed in recreational players than the more skilled players (p < 0.005). Conclusions In conclusion, the 9-ball test protocols were reliable and could successfully discriminate between different playing levels. Coaches and researchers may employ these protocols to identify errors, monitor training, and rank players.

Comparative experimental research on falling ball test method and K30 plate load method on foundation of different structures

In highway and railway foundation projects, the mechanical properties of foundation materials are one of the main indicators of construction process control. The elastic modulus of foundation directly affects road surface deflection and must be tested. The falling ball test method and the K30 plate load method are widely used in engineering, In order to explore the relationship between the two methods and guide the engineering application, the falling ball test method and the K30 plate load method are applied to homogeneous materials (homogeneous fine-grained material layers) and layered materials(Old foundation).Through comparative test, we found that there is a strong correlation between the falling ball test method the K30 plate load method in some scenarios,which can be used for mutual reference in engineering experiments.

The relationship of concentration and eye-hand coordination with accuracy of backhand backspin serve in table tennis

The purpose of this study was to analyze the relationship between concentration and hand eye coordination with the accuracy of backhand backspin service. Quantitative approaches and correlational methods are used in this study. This research was conducted at PTM Gempas. The population in this study were all cadet athletes at PTM Gempas, while the sampling technique used was saturated sampling, which means that all athletes totaling 20 people were used as samples. Player concentration data is collected using a concentration grid test, hand eye coordination data is obtained by throwing a tennis ball test, and data for backhand backspin service accuracy is obtained by testing servicing. The results of this study are as follows: 1) Concentration has a strong enough relationship with the accuracy of backhand backspin service, 2) Hand eye coordination has a strong enough relationship with backhand backspin service accuracy. 3) Concentration and hand eye coordination together have a strong enough relationship with backhand backspin service accuracy. Table tennis coach should train the concentration and eye-hand coordination to improve the athlete's service accuracy.

HUBUNGAN KESEGARAN JASMANI DENGAN KEMAMPUAN SHOOTING DALAM PERMAINAN SEPAK BOLA PADA PEMAIN PS. ANDESKAL MUDA KOTA BENGKULU

This study aims to determine the relationship of Physical Freshness and Shooting Ability in Football Games on PS Players. Andeskal Muda City of Bengkulu. This type of research is correlational with quantitative methods. The population in this study were PS players. Andeskal Muda Bengkulu City, amounting to 30 people. While the sampling technique was done by using the total sampling technique. Thus, the sample size is 30 people. Data was collected using the Indonesian Physical Fitness Test (TKJI) and the shooting ability test was carried out by the shooting at the ball test. The level of physical fitness of PS players. Andeskal city of Bengkulu had the lowest score of 11 categories with less and the highest score of 22 which was very good category, and the shooting ability had the lowest score of 24 poor categories and the highest score was 47 which was very good category. The results showed that the level of physical fitness of the players had a relationship with the results of the shooting ability of the PS players. Andeskal Muda city of Bengkulu, based on the value of rtable in the product moment obtained 0.361 then rejected Ho in the t analysis test obtained, tcount was 6.1978 greater than ttable is 2.048, the decision rejected the alternative hypothesis (Ho) and accepted the alternative hypothesis (Ha). So the conclusion is that there is a correlation between the TKJI test (variable x) and the shooting ability test (variable y) on PS players. Andeskal Muda city of Bengkulu, this is shown by the correlation coefficient of 0.76 which is in the strong category.