Categorie: BDI Articole

QUALITATIVE CORRELATION BETWEEN FRICTION COEFFICIENT AND METAL SURFACE WEAR IN THE CASE OF LINEAR FRICTION DRY CONTACT WITH REINFORCED POLYMERS WITH GLASS FIBRE

Composite thermoplastic materials are biphasic materials consisting of a mass of polymer and the reinforcement embedded in it. The polymer provides the compressive strength of the material, while the reinforcement improves the tensile strength. Homogeneity of the material and its cohesion has an important role in obtaining some good mechanical characteristics. Thus, the disposal of the reinforcement considerable influences the tensile strength feature. Also the elasticity of the polymer can improve the compression resistance or bending resistance of the reinforcement material. The role of the basic polymer is first of all mechanical and is to provide the bond with the reinforcement fibres. It is the one that transmits the efforts between the reinforcement fibres.  Read more

Scratch and cyclic impact testing of adhesion PLD coatings, Ti-N on SS316L substrate

The method introduced by W. C. Oliver and G.M. Pharr in 1992 for hardness and elastic modulus measuring by instrumented indentation technique was adopted and used widely in mechanical behavior characterization of materials at the small scales [1]. Its appeal derives largely from the fact that mechanical properties can be determined directly from indentation loading measurements and of movement without having to view the hardness imprint. With high resolution testing equipment, it facilitates measurement of the properties to the micrometer and nanometric scales. Therefore, this method has become a primary technique to determine the mechanical properties of thin films and small structural features.  Read more

Conical pin wear in ceramics materials cyclic impact testing

Penetrator tip wear was investigated on an apparatus testing the impact on hard ceramic materials. The experimental tests were done on a vertical impact computerized test bench of original conception. Tapered diamond and carbide-metal pins were used as penetrators. It was noticed that in some situations the tip of the penetrator remained stuck in its target, acting as a Morse cone, due to the friction force between the penetrator and its target being higher than the reaction force of the collision between the two objects. Read more

THE MUTUAL INFLUENCE OF THE INPUT AND OUTPUT PARAMETERS ON THE IN TIME EVOLUTION OF A POLYMER ON STEEL TRIBOSYSTEM WITH LINEAR DRY CONTACT

Ever since the year 1964 Bowdon and Tabor [1] experimentally found that the values of the friction coefficients of the „clean” metals couples on plastic materials and in the presence of some moderate loads are similar to those of the plastic material / plastic material friction couplings. They considered that the shear force is due to friction of the micro-junctions formed on the contact surface of the two samples. Read more

QUANTITATIVE-QUALITATIVE CORRELATION OF STEEL SURFACE FRICTION-WEAR PROCESS IN LINEAR DRY CONTACT WITH SGF REINFORCED POLYMERS

In this paper, we present a quantitative – qualitative correlation, based on extensive experimental determinations between the value and the evolution of the friction coefficient, wear of steel surfaces and contact temperature, in the case of linear dry contact, for thermoplastic material reinforced with short glass fibers (SGF) and various steel surfaces.  Read more

Wear of Polished Steel Surfaces in Dry Friction Linear Contact on Polimer Composites with Glass Fibres

It is generally known that the friction and wear between polymers and polished steel surfaces has a special character, the behaviour to friction and wear of a certain polymer might not be valid for a different polymer, moreover in dry friction conditions. In this paper, we study the reaction to wear of certain polymers with short glass fibres on different steel surfaces, considering the linear friction contact, observing the friction influence over the metallic surfaces wear. The paper includes also its analysis over the steel’s wear from different points of view: the reinforcement content influence and tribological parameters (load, contact pressure, sliding speed, contact temperature, etc.). Read more

Wear modeling of steel surfaces to the flow under pressure of melts polymers with SGF

Any melted polymer can be found in different temperature and pressure conditions. The tribological behaviour of the metal/plastic couple, in the case of viscous flowing state of the plastic material, is a particular case, very little studied. Bartenev and Lavrentiev [1] show that as a consequence of the slight deformations of the polymers in such conditions a fictive contact area, comparable as a notion with solid bodies’ nominal contact area, is formed at the separation surface with a solid body [2]. In this situation, even for small adhesions of the polymer with the solid’s surface, tangential shearing stresses, that exceed the value of maximum shearing efforts from the fluid material’s volume, appear on the contact area [3]. This makes for the pure external friction not to manifest itself, which is one of the experimental difficulties in studying this kind of friction.

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Modeling Possibilities of Very High Temperatures and Pressures at Friction Contact Plastics Filled with Glass Fibers on Steel

Abstract Often for the laboratory studies, modeling of specific tribological processes raises
special problems. One such problem is the modeling of some temperatures and extremely
high contact pressures, allowing modeling of temperatures and pressures at which the
injection or extrusion processing of thermoplastic materials takes place. Tribological
problems occur mainly in thermoplastics materials reinforced with glass fibers.

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Aspects of the influence of hardness on the dry friction coefficient at a Timken type couple, plastic reinforced with glass fibers/steel

Abstract Thermoplastic materials reinforced with glass fibers can be used in various fields,
and their properties were recognised a long time ago. Among them is the machines and
different equipment construction field, where thermoplastics give good results as substitutes
in machines parts manufacturing. This new application is due to some of these materials’
qualities, as its specific light weight, satisfying mechanical resistance, high possibilities to
work in a corrosive environment, good behaviour to friction and wear, etc.

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A qualitative correlation between friction coefficient and steel surface wear in linear dry sliding contact to polymers with SGF

In this paper we tried to present a qualitative correlation, based on extensive experimental determinations between the value and the evolution of the friction coefficient, wear, and contact temperature, in the case of linear dry contact, for thermoplastic material reinforced with short glass fibers (SGF) and various steel surfaces. The aim was to highlight the evolution of the wear process depending on the evolution of the friction coefficient. As a result, it was possible to graphically illustrate the evolution of the friction coefficient and the change of the wear process, emphasizing the abrasive, adhesive and corrosive wear.

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LINEAR PIPE ROBOT INSPECTION „RICL 14”

Indrumator : Rus Dorin Absolvent : Ovidiu Craciun Iulian

QUALITATIVE CORRELATION BETWEEN FRICTION COEFFICIENT AND METAL SURFACE WEAR IN THE CASE OF LINEAR FRICTION DRY CONTACT WITH REINFORCED POLYMERS WITH GLASS FIBRE

Composite thermoplastic materials are biphasic materials consisting of a mass of polymer and the reinforcement embedded in …

Scratch and cyclic impact testing of adhesion PLD coatings, Ti-N on SS316L substrate

The method introduced by W. C. Oliver and G.M. Pharr in 1992 for hardness and elastic modulus measuring by instrumented indentation …