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Antiwear mechanism of action of some chemical elements added to lubricant is studied. These elements are transferred from the lubricant into the surface layers of the…
Antiwear mechanism of action of some chemical elements added to lubricant is studied. These elements are transferred from the lubricant into the surface layers of the sliding pair during friction. The mechanism is based on the influence of these elements on the stacking fault energy (SFE) of the materials in the friction pair and leads to changes in the fragmented structure formed in the metals under plastic deformation. Work hardening of the metal surface layers and their predisposition to wear are changed accordingly. Copper and Armco iron, as typical FCC and BCC metals, were chosen for the friction pair materials. Si, Ni, Zn, Co and Ti were used as the additive components to the lubricant. It was found that the addition of different elements to the lubricant leads to alloying by these elements of the surface layers of the metal during the process of friction. It was found that alloying by elements which decreases the SFE of the metal, the average size of surface layer fragments formed during friction increases and the wear rate decreases. The possibility of controlling the wear resistance of metals during friction through the use of appropriate additives is discussed.
This work aims to investigate the wear behavior of manganese phosphate coating on plasma nitrided AISI 5140 steel.
Prior to manganese phosphate coating, plasma nitriding of substrates was performed at gas mixture of 50 percent H2 and 50 percent N2, for the different treatment parameters. The structural, mechanical and tribological properties of the substrates were determined using hardness test, optical microscope, scanning electron microscopy , X‐ray diffraction and pin‐on‐disk tribotester. The wear behavior of untreated, nitrided and duplex treated substrates was evaluated under dry sliding conditions.
The results indicated that the duplex treatment improved the wear behavior. It was also observed that manganese phosphating of the nitrided substrates at low temperature (450°C‐2h‐N) resulted in a decrease of the wear rate and yielded a reduction in the friction coefficient by forming a transfer film at the counter face.
This study can be a practical reference and offers insight into the effects of duplex treating on the increase of wear resistance.
This paper aims to examine empirically the role of toeholds in reducing asymmetric information in mergers and acquisitions by establishing a relationship between the…
This paper aims to examine empirically the role of toeholds in reducing asymmetric information in mergers and acquisitions by establishing a relationship between the toehold and some relevant characteristics of the acquiring and the target firm.
A regression analysis is conducted to examine the relation between the dependent variable (the toehold) and a set of independent variables. A multinomial logit model is used to test for the occurrence of toeholds. A probit selection model and two-step Heckman correction tests are used to correct the data and to check for robustness of the results.
The regression results for acquisitions with prior toeholds are consistent with the studied hypotheses that asymmetric information is more observed in foreign acquisitions, in different industries, with tender offers and with higher levels of intangible assets. A negative relationship is found between toehold size and the number of competing bidders.
Consistent with previous literature, the study finds that majority of bidders abstain from purchasing a toehold before entering a bid contest. The study also emphasizes the role of intangible assets in assessing the efficacy of toeholds under asymmetric information. The ratio of target intangible assets to target total serves as a proxy for asymmetric information. Regression results are consistent with the hypotheses that asymmetry of information is observed when the acquiring and the target firm operate in different countries and industries.