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Hard Coatings (hard + coating)
Selected AbstractsInvestigations on Nanolaminated TiZrN/CrN as a Tribological PVD Hard Coating for Incremental Sheet Forming Tools,ADVANCED ENGINEERING MATERIALS, Issue 8 2009Kirsten Bobzin PVD coated metal forming tools may enormously reduce tool and work piece wear, friction and forming capacities. A PVD deposited TiZrN/CrN + CrN material system is presented for application on incremental sheet forming tools. This work reports on coating process development and tribological investigations leading to a clear friction reduction and wear protection. [source] Nanocomposite Hard Coatings: Deposition Issues and Validation of their Mechanical Properties,ADVANCED ENGINEERING MATERIALS, Issue 5 2005P. Schwaller Abstract The limitations of conventional coatings due to inferior hardness or poor oxidation stability can be overcome by nanocomposite hard coatings such as nc-TiN/a-SiNx, which consists of nanocrystalline TiN and a non-crystalline tissue phase of SiNx which are mutually immiscible. The properties of nanocomposite coatings, especially their increased hardness, can be explained by their nanostructure, which leads to a maximum hardness at typically 80 atomic percent of the crystalline phase. We show that enhanced hardness can only be attained when the silicon nitride phase is sufficiently nitrided. The accurate and reliable measurement of the hardness and elastic modulus requires the use of appropriate nanoindentation equipment and a careful tip correction with periodical validation. It is shown that for a correct hardness determination of a few microns thick nanocomposite coatings, an indentation depth of 100,nm is sufficient. The maximum hardness of our nc-TiN/a-SiNx coatings deposited by a hybrid UBM/arc-PVD process is about 40,GPa. This value represents a global hardness value, due to the nanocomposite structure there may be a local hardness variation of about ±10,%. [source] Use of average value of Langmuir probe characteristic for characterization of pulsed dischargesCONTRIBUTIONS TO PLASMA PHYSICS, Issue 7 2003J. Bla Abstract Based on numerical calculations a new method has been developed, which enables plasma analysis from the average value of the Langmuir probe current measured in pulsed discharge. The application of this method for characterization of a planar reactor used for plasma enhanced chemical vapor deposition of TiN and (TiAl)N hard coatings is described as an example. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Nanocomposite Hard Coatings: Deposition Issues and Validation of their Mechanical Properties,ADVANCED ENGINEERING MATERIALS, Issue 5 2005P. Schwaller Abstract The limitations of conventional coatings due to inferior hardness or poor oxidation stability can be overcome by nanocomposite hard coatings such as nc-TiN/a-SiNx, which consists of nanocrystalline TiN and a non-crystalline tissue phase of SiNx which are mutually immiscible. The properties of nanocomposite coatings, especially their increased hardness, can be explained by their nanostructure, which leads to a maximum hardness at typically 80 atomic percent of the crystalline phase. We show that enhanced hardness can only be attained when the silicon nitride phase is sufficiently nitrided. The accurate and reliable measurement of the hardness and elastic modulus requires the use of appropriate nanoindentation equipment and a careful tip correction with periodical validation. It is shown that for a correct hardness determination of a few microns thick nanocomposite coatings, an indentation depth of 100,nm is sufficient. The maximum hardness of our nc-TiN/a-SiNx coatings deposited by a hybrid UBM/arc-PVD process is about 40,GPa. This value represents a global hardness value, due to the nanocomposite structure there may be a local hardness variation of about ±10,%. [source] Tribological interactions between DLC coatings and lubricantsLUBRICATION SCIENCE, Issue 2 2008B. Podgornik Abstract In the last couple of years a tremendous research work has been done in the field of development and characterization of hard coatings, mainly to boost their use in machine component applications working under normal and extreme operating conditions. Generally, hard coatings improve tribological properties of contact surfaces under dry sliding, while under lubricated conditions their inertness hinder the possibility of boundary film formation. The aim of this paper is to elaborate on the interactions between diamond-like carbon (DLC) coatings and lubricants, and possible tribofilm formation in different tribological contacts. Therefore, relationships between surface properties (i.e. surface tension, surface free energy, contact angle) and tribological properties of the lubricated DLC coated contact, as well as the influence of oil additive type and concentration and contact conditions will be presented. It is believed that this type of knowledge will lead to further coatings modification in terms of improved tribological properties under boundary lubrication. Copyright © 2007 John Wiley & Sons, Ltd. [source] Tribological characterisation of hard coatings with and without DLC top layer in fretting testsLUBRICATION SCIENCE, Issue 1 2006D. KlaffkeArticle first published online: 14 DEC 200 Abstract The potential of coatings to protect components against wear and to reduce friction has led to a large variety of protective coatings. In order to check the success of coating modifications and to find solutions for different purposes, initial tests with laboratory tribometers are usually done to give information about the performance of a coating. Different Ti-based coatings (TiN, Ti(C,N), and TiAlN) and NiP were tested in comparison to coatings with an additional diamond-like carbon (DLC) top coating. Tests were done in laboratory air at room temperature with oscillating sliding (gross slip fretting) with a ball-on-disc arrangement against a ceramic ball (Al2O3). Special attention was paid to possible effects of moisture (relative humidity). The coefficient of friction was measured on line, and the volumetric wear at the disc was determined after the test from microscopic measurements of the wear scar and additional profiles. The friction and wear behaviour is quite different for the different coatings and depends more or less on the relative humidity. The DLC coating on top of the other coatings reduces friction and wear considerably. In normal and in moist air the coefficient of wear of the DLC top-layer coating is significantly less than 10,6,mm3/Nm and the coefficient of friction is below 0.1. In dry air, however, there is a certain tendency to high wear and high friction. Copyright © 2006 John Wiley & Sons, Ltd. [source] A method for the tribological testing of thin, hard coatingsLUBRICATION SCIENCE, Issue 2 2002R. Michalczewski Abstract A new method has been developed for tribological testing of thin, hard antiwear coatings, using a ball-on-disc tribosystem, under conditions of dry sliding. In this, an Al2O3 ball is pressed against a coated steel disc. Wear debris is removed from the contact zone by a stream of dry argon in this novel method. This improves the stability of the tribological properties and the repeatability of the test results. All test conditions are precisely defined, in particular: the type of motion, air relative humidity, ambient temperature, sliding speed, load, tribosystem spatial configuration, substrate material, substrate hardness and roughness, and coating thickness. The method developed has been used to test various physical vapour deposition coatings (deposited by the vacuum arc method), i. e., single-layer TiN, Ti(C,N), CrN, and Cr(C,N), and multilayer Cr(C,N)/CrN/Cr and Cr(C,N)/(CrN+Cr2N)/CrN/Cr. It is shown that CrN coatings exhibit the best antiwear properties, and Ti(C,N) the worst. Friction coefficients for CrN and Cr(C,N) coatings are much lower than for the more commonly used TiN. Multilayer coatings have better antiwear properties than single-layer ones. [source] Werkzeugbeschichtungen für die Trockenbearbeitung,MATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 10 2006E. Abele PVD coating; tribology; dry machining; tool wear Abstract Bei der Trockenbearbeitung wirkt an der Werkzeugschneide ein Belastungskollektiv aus mechanischen, thermischen und chemischen Einflussgrößen. Im Vergleich zur konventionellen Bearbeitung unter Verwendung von Vollstrahl-Emulsionskühlung erhöht die Trockenbearbeitung die auf den Schneidkeil wirkenden Belastungen. Eine sehr gute Möglichkeit die Schneide vor thermischen, abrasiven und tribo-oxidativem Verschleißangriff zu schützen stellt die Verwendung von PVD Beschichtungen dar. Neu entwickelte PVD Beschichtungen aus CrxAlyYzN, CrxAlyBzN und CrxAlySizN- wurden sowohl im tribologischen Modelltest als auch im realen Zerspanungstest auf ihre Eignung zur Trockenbearbeitung untersucht. In diesem Paper wird neben der verwendeten Beschichtungstechnologie detailliert auf die Schichteigenschaften eingegangen. Im Zusammenhang mit dem im Zerspanungstest gemessenen Verschleißverhalten und der Prozesskräfte werden anschließend Rückschlüsse auf das weitere Optimierungspotential dieser Schichtsysteme gezogen. Tool coatings for dry machining During dry machining a strain collective consisting of mechanical, thermal, and chemical loads is imposed upon the cutting edge. Compared to conventional machining using cooling lubrication fluids, the loads are increased in dry cutting. A feasible solution to protect the cutting edge from thermal wear, abrasion, and tribo-oxidation is the application of hard coatings. Newly developed CrxAlyYzN, CrxAlyBzN and CrxAlySizN PVD coatings were both evaluated in tribological model tests and machining tests concerning their suitability for dry cutting applications. Herein, the used coating technology and the coating properties are described in detail. The measured tool wear and the process forces give further hints for the optimization of the coating system. [source] Damage Phenomena Observed on PVD Coatings Submitted to Repeated Impact TestsPLASMA PROCESSES AND POLYMERS, Issue S1 2007Florent Ledrappier Abstract Thin hard coatings obtained by PVD process are widely used to improve the mechanical and friction behaviour of industrial parts. Depending on the friction conditions, the failure mechanisms and resulting selection criteria may be very different. This study aims to investigate the endurance life of some PVD coatings under repeated impact conditions. Impact tests at controlled impact energy have been performed using a hemispherical tip. Long-term tests have been done to determine the coating endurance life while short tests enable us to identify the damage phenomena. Depending on the nature of the PVD coating, cracks, blisters or spalling may be observed under impact. These phenomena may worsen until the complete film rupture occurs. [source] | ||||||||||