カルボン酸の低摩擦特性に及ぼす分子配向の影響

Molecular alignment is a key to achieve an ultra-low friction coefficient. We found that friction coefficient decreased 49% when oleic acid (OAc) was added in poly-α-olefin (PAO), while only decreased 19% when added in polypropyleneglycol (PPG). FT-IR analysis indicates that the dimers of OAc became more easily aligned parallel to the sliding direction in PAO than in PPG. The associated carboxylic acids (OAc-PBAc), which feature two rings in the structure, an eight-membered cyclic carboxylic acid and a benzene ring, also decreased friction coefficient dramatically. FT-IR analysis indicates that the eight-membered cyclic carboxylic acid and the benzene ring were oriented parallel to the shearing plane. The oriented molecules led to low friction coefficient. Our results provide key insights into achieving ultralow friction coefficient through the design of the large, flat structures in lubricant molecules.本研究は、2017年度関西大学若手研究者育成経費（個人研究）において、研究課題「潤滑剤分子の配向によるスマート潤滑システムの創成」として研究費を受け、その成果を公表するものである。第22回関西大学先端科学技術シンポジウム関西大学千里山キャンパス100周年記念会館2018年1月18日（木）・19日（金

Effect of Temperature on Friction Properties of Associated Carboxylic Acids under Boundary Lubrication

本研究は平成29年度関西大学若手研究者育成経費の助成を受けたものである。会議名：トライボロジー会議 2017 春東京 開催地：国立オリンピック記念青少年総合センター会期：2017年5月15日（月）～17日（水）主催者：一般社団法人日本トライボロジー学

DEVELOPMENT OF PHOTOELECTRON-ASSISTED CHEMICAL VAPOR DEPOSITION

We developed a photoelectron-assisted chemical vapor deposition (PACVD) that can deposit an ultra-thin perfluoropolyether (PFPE) film on a diamond-like carbon (DLC) surface. The DLC surface with a 1 nm-thick PFPE film deposited by the P ACVD showed a low surface energy. The surface also showed a low adhesion force that was caused by the low surface energy. We confirmed that the PFPE/DLC surface deposited by the PACVD has the potential to improve the areal density of hard disk drives.This work was supported in part by Kansai University, Outlay Support for Establishing Research Centers in 2014, a Kansai University Grant in Aid for the Promotion and Upgrading of Education and Research, and MEXT KAKENHI grant number 15H02216

Alkylated Polyphenyl Ethers as High-Performance Synthetic Lubricants

Lubricants exhibiting both thermal and chemical stability that consequently generate less hydrogen during friction are required to avoid the hydrogen embrittlement of moving mechanical components. The present work studied the effects of the length and number of alkyl chains on the tribological properties of polyphenyl ethers (PPEs), which feature good thermal and radiation resistance. PPEs were found to have much lower friction coefficients compared with a poly-alpha-olefin and alkyldiphenyl ether, and the effect of the running-in process on friction appeared to be negligible. The formation of polymers on the friction track evidently decreased the friction coefficients of the lubricants and the wear rates were almost zero for all the PPEs, indicating excellent anti-wear properties. Analyses with a quadrupole mass spectrometer connected to a friction tester under vacuum indicated negligible hydrogen generation from 4P2E, which had no alkyl chains, after the running-in. R1-4P2E, having a C16H33 chain, showed hydrogen desorption similar to that of the alkyldiphenyl ether, which had a C18H37 alkyl chain. R2-4P2E, with two C16H33 chains, produced significant hydrogen, but with a long induction period; thus, it provided good wear protection. Although alkyl chains increased the risk of hydrogen generation, PPEs with such chains may have applications as standard lubricants

Effects of Oxygen on Smear Formation in Heat Assisted Magnetic Recording System

Heat-assisted magnetic recording (HAMR) is expected to be a realistic next-generation technology for increasing the recording density of hard disks. However, the magnetic layer is heated above the Curie temperature, and, as a result, the heated lubricant is desorbed from the disk by decomposition and evaporation, which causes a problem as it adheres to the air-bearing surface (ABS) as a smear. In this study, pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) analysis was performed in helium and air environments to investigate the decomposition mechanism of perfluoropolyether (PFPE) lubricant D-4OH by heating and in the presence of oxygen. In the helium environment, thermal decomposition of the end groups was confirmed at 350°C and above with a possibility of main chain decomposition at 450°C. In the air environment, decomposition of the end group was confirmed at 250°C and above, and decomposition of the main chain was confirmed at 450°C. Experiments using a pin-on-disk tester were conducted to confirm what happens to the area of smear when a thin film of D-4OH lubricant coated on an actual disk is laser heated. As a result, it was confirmed that the area of smear decreased even at an oxygen concentration of 5%