Composite layers with ceramic matrix modified with glassy carbon destined for oil-less sliding pairings

The paper presents basic knowledge about producing and some results of tribological and metallographical research on composite layers with porous, anodic hard coating matrix which were modified with glassy carbon nanotubes. These composite layers were formed as surface layers of machine parts operating under conditions of sparse lubrication (limited lubrication) and friction in air. The layers were tested at sliding mating with EN-GJL-350 cast iron used for piston rings in combustion engines and air compressors. On the basis of the metallographical tests was the structure of the composite layer described. It was fount that on the surface of the oxide is a glassy carbon layer and in the pores of oxide are regullary carbon nanotubes. On the basis of the obtained results of tribological tests it was found that glassy carbon layer on the oxide surface shorts the wering-in time, and the glassy carbon nanotubes formed inside the pores of anodic hard coating upon EN-AW-6061 aluminum alloy prove to be effective solid lubricants and complement lubrication function of the graphite in cast iron. Consequently the coefficient of friction was lower than in case of nanotubes-free oxide layers

Properties of aluminium-ceramic composite with glassy carbon as solid lubricant designed for automotive applications

The paper presents some basic information on manufacturing, structure and selected properties of a new hybrid composite with an aluminium alloy matrix elaborated for automotive applications. A porous oxide ceramics constitute the reinforcing phase of the composite and glassy carbon plays the role of a solid lubricant. The properties of a composite, which contains exclusively a ceramic reinforcing phase and a hybrid composite with porous ceramics and glassy carbon, have been compared. The composite with glassy carbon, obtained by the application of new method, features uniform carbon distribution upon ceramics walls which significantly influences its tribological properties. The friction in air coefficient of a hybrid composite sliding against grey cast iron is 0.12, whereas in the case of a composite containing exclusively ceramics sliding against cast iron it amounts to 0.3

3D model of anodic oxide coating modified with carbon particles

In this paper shown three-dimensional model of composite hard anodic layer modified by carbon particles. Modifications were carried by vacuum sublimation by a graphite electrode. The modified layer is characterized by improved tribological properties (friction coefficient) compared to the unmodified layer. Test conditions and values of the coefficients of friction are presented for the combination of pin-on-disc pair in T-01M tester. The 3D model was made in parametric CAD program Solid Edge v19 pl, which allows to explain the decrease in the coefficient of friction

Tribological characteristics of AOC modified with carbon particles and nano-pipes

The paper represents the results of investigations conducted on the tribological tester T-01 on pinon- disk pair for the conditions of the friction of technically dry. Analysis stereological counterspecimen was subjected from AOC and AOC modified with carbon particles and nano-pipes, that is composites coats. The values of the coefficient of the friction and the parameters of the roughness are presented, to four groups of samples

Tribological properties of aluminium oxide layer modified by carbon

The article presents the tribological and stereometric properties of aluminium oxide layers modified by carbon. The coatings were produced on EN-AW-5251 aluminium alloy substrate using a two-stage technology. The matrix composite coating made the oxide layer produced via hard anodising method, which was then modified with the vacuum deposition method. Coatings were investigated in connection with PEEK/BG and T5W materials. Tribological tests were carried out on T-17 tester in reciprocating motion under lubricant-free sliding condition

Tribological properties of oxide anodic layers modified with carbon particles and nanotubes

Oxide coatings are known and have been used for many years. Higher and higher requirements, which lubricant free couplings or couplings with limited lubrication have to meet, initiated trials of their modification. Modifications preserve all advantages of the oxide layer, and they improve their operating properties (e.g. a decrease in the friction coefficient or wear intensity of co-partners). Tribological test results of the modified APT layers in a coupling with the PEEK/BG material in the mandrel-disk system are presented in the article. Oxide anodic layers, which were obtained on the EN AW-5251 aluminum alloy in the ternary electrolyte, have been examined in the work. Three types of the oxide layer modification were used in a form of an addition of graphite powder to the electrolyte during the production; by vacuum sublimation by means of a graphite electrode, and modifying the base layer with nano-particles. The non-modified oxide layer was used as a reference point. The modification resulted in an improvement of tribological characteristics in co-operation of the layer with the PEEK/BG material, in particular, for the modification with nano-tubes. Values of the initial and stabilised friction coefficient were significantly lower, which had an influence on higher dimension stability during experiments. In spite of the expectations the oxide coating, which was made in the ternary electrolyte with the graphite powder addition did not have significantly lower values of the friction coefficient comparing to the non-modified layer, while the wear intensity of the PEEK/BG material was higher

Properties of an anodic oxide coating modified by the application of a polymer for a friction pair in reciprocating motion

The paper represents the results of investigations conducted on a tribological test for technically dry conditions of the friction. Analysis of the stereological counter-specimen was subjected from AOC and AOC modified sealed up the polymers that is composites coats. Polymerisation occurred at a temperature below the recrystallization temperature of the alloy EN AW 5251. The values of the coefficient of the friction, the results of investigations AFM, and the parameters of the roughness were compared. The tribological properties of the composites are investigated using the pin-on-plate type wear tester T-17. This paper shows 3D models of the AOC modified polymer and the mechanism of wearing. Tribological measurements show the reduced wear and friction of the composite coatings as compared with the pure anodic oxide