No abstract

A series of monooxotungsten(iv) and dioxotungsten(vi) benzenedithiolates, (NEt)[WO(1,2-S-3-RCONHCH)] (1-W; R = CH (a), t-Bu (b), or CF (c)) and (NEt)[WO(1,2-S-3-RCONHCH)] (2-W), were synthesized and compared with the corresponding molybdenum analogues. Single crystals of trans-1b-W were successfully obtained, and the crystal structure was determined by X-ray analysis although 1b-Mo could not be crystallized. The NHS hydrogen bonds shifted the potential of the W(iv/v) redox couple to more positive values, and the strength of the hydrogen bond and the positive shift value were strongly correlated. The hydrogen bonds in both 1-W and 2-W were weaker than those in the corresponding molybdenum analogues; however, the effect of the hydrogen bonds on the redox potential was greater in 1-W.

This study was conducted to invcstigate effect of DLC (diamond − like carbon) multi − layer coating oll fat ． igue pr 〔 〕 perties of stainless steel SUS304 ． The DLC muhi − layer of 2 ． 2 爆 τ ｝ thickness possessed a laminated struct ． ul ℃ conlposed ')f very thin DLC layers in which hardness was different ． This structure was selected to prevent loss of the functionalities of thc DLC layer through fracture or peeling which cou 】 d occur under impact force ． The DLC multi 一 工 ayer was generated by UBMS (unbalallc 巳 d magnetron sputter ［ rlg)method ． Th 巳 resu ！ t showed thaL tnicrostructure of the substrate was unchanged by the DLC multi − layer coating conductcd at relatively Iow temperature ， so that the mechanical properties was maintained to thc same Ievel of tbc untreated material ． The fatigue strength was irnproved by the DLC mu 正 ti Iaycr cQating sirlce the Iayer havirlg a high strength sumciently adhered tQ thc substrate and prevented initiation of futigue cracks fr〔｝rn the surface ． However ， its fatigue strength was sl ｛ ghtly k ユ wer than that of the m 呂terial c ') ated by DLC single layer， Such dif「 erence in thc fatigue strength betwccn the materia ］ scoated by the DLC multi − layer and singte − layer would result from t ． he differcnce in the fracture streng 亡