Modern coatings in high performance cutting applications

Modern, state-of-the-art, PVD coatings are required to fulfill a variety of different applications. Each metal cutting operation requires an optimal combination of various film parameters to achieve a high end cutting performance. Especially, Al-based coatings such as AlTiN- and AlCrN-coatings show very good results in high performance metal cutting applications. Wear resistance, thermal stability such as oxidation resistance and hardness at elevated temperatures are key issues within these cutting operations. In this paper the influence of these properties on Al-based nitride coatings in relation to metal cutting tests such as milling and drilling will be discussed

Risk-shifting Through Issuer Liability and Corporate Monitoring

This article explores how issuer liability re-allocates fraud risk and how risk allocation may reduce the incidence of fraud. In the US, the apparent absence of individual liability of officeholders and insufficient monitoring by insurers under-mine the potential deterrent effect of securities litigation. The underlying reasons why both mechanisms remain ineffective are collective action problems under the prevailing dispersed ownership structure, which eliminates the incentives to moni-tor set by issuer liability. This article suggests that issuer liability could potentially have a stronger deterrent effect when it shifts risk to individuals or entities holding a larger financial stake. Thus, it would enlist large shareholders in monitoring in much of Europe. The same risk-shifting effect also has implications for the debate about the relationship between securities litigation and creditor interests. Credi-tors’ claims should not be given precedence over claims of defrauded investors (e.g., because of the capital maintenance principle), since bearing some of the fraud risk will more strongly incentivise large creditors, such as banks, to monitor the firm in jurisdictions where corporate debt is relatively concentrated

Off-axis texture in nanostructured Ti1-xAlxN thin films

Standard theta-2 theta and pole figure X-ray diffraction techniques were used to study structural properties and preferred orientation of nanostructured TiAIN thin films prepared using cathodic are deposition. Systematic collection of reflections from lattice planes {111}, {200}, {220}, and {311} showed that the in-plane orientation of crystallites exhibits cylindrical symmetry with random distribution of crystallites, while the out-of-plane growth presents strong texture which is inclined with respect to the surface normal. This brings the crystallographic orientation of fibre texture towards high indices lattice planes (113) and (115) contrary to traditionally grown films that develop a preferred orientation following to low indices close-packed planes (111) and (200). The origin of inclined growth is discussed taking into account the role of crystallographic defects in particular twin faults that develop in the lattice of growing crystal and change the stacking sequences of atom layers. (c) 2007 Elsevier B.V. All rights reserved

Oxidation post-treatment of hard AlTiN coating for machining of hardened steels

In this study, cemented carbide ball nose end mills with nano-crystalline Al0.67Ti0.33N hard PVD coatings deposited by cathodic arc evaporation were annealed at 700 °C during 2 h in a controlled atmosphere environment (argon + oxygen mixture) and in vacuum. The changes of structure and properties of the treated coating surfaces have been analyzed using both cross-sectional scanning electron microscopy (SEM) and x-ray absorption spectroscopy (XAS) of the N–K and O–K edges. Cutting tools have been run through ball nose end milling of hardened H13 steel (HRC 50) where temperature or stress dominating phenomena control tool life. The data obtained indicate that an AlTiN coated cutting tool can be modified upon annealing at low temperature conditions and should be considered as a composite surface engineered material. It is shown that increased tool life could be achieved if annealing of AlTiN is performed in an oxygen-containing atmosphere. A variety of different characteristics should be optimized to achieve better wear resistance of the cutting tools with annealed Al0.67Ti0.33N coating under high temperature and stress cutting conditions.Ministerio de Educación y Ciencia MAT2007-66719-C03-03Ministerio de Educación y Ciencia CSD2008-00023 (Consolider

Friction and wear behavior of WS2/Zr self-lubricating soft coatings in dry sliding against 40Cr hardened steel balls

WS[subscript 2] and WS[subscript 2]/Zr self-lubricating soft coatings were produced by medium-frequency magnetron sputtering, multi-arc ion plating and ion beam assisted deposition technique on the cemented carbide YT15 (WC+15%TiC+6%Co) substrates. Microstructural and fundamental properties of these coatings were examined. Sliding wear tests against 40Cr hardened steel using a ball-on-disk tribometer method were carried out with these coated materials. The friction coefficient and wear rates were measured with various applied loads and sliding speeds. The wear surface features of the coatings were examined using SEM. The results showed that the WS-1 specimen (with WS[subscript 2]/Zr composite coating) has higher hardness and coating/substrate critical load compared with that of the WS-2 specimen (only with WS2 coating). The friction coefficient of WS-1 specimen increases with the increase in applied load, and is quite insensitive to the sliding speed. The wear rate of the WS-1 specimen is almost constant under different applied loads and sliding speeds. The WS-1 specimen shows the smallest friction coefficient and wear rate among all the specimens tested under the same conditions. The WS-1 specimen exhibits improved friction behavior to that of the WS-2 specimen, and the antiwear lifetime of the WS2 coatings can be prolonged through adding Zr additives. The self-lubricating and wear mechanism of the WS[subscript 2]/Zr coating was also found from the sliding wear tests

The link between supervisory board reporting and firm performance in Germany and Austria

Corporate governance research, Supervisory board, Audit committees, Board independence, Financial expertise, External audit, M4, H1, K2, G3,