Interpretation of the Friction Coefficient During Reciprocating Sliding of Ti6Al4V Alloy Against Al2O3

Tribological behaviour of Ti6Al4V alloy, during linear reciprocating sliding against alumina, at nanotribometer (ball-on-flat type of contact) was investigated. Experiments were carried out for sliding in Ringer's solution, over a range of loads (100 - 1000 mN) and speeds (4 - 12 mm/s). Friction behaviour of the contact pairs was investigated by analysis of the dynamic friction coefficient plots and effective root mean square (rms) coefficient of friction, COFrms. Presented mathematical envelopes of dynamic coefficient of friction curves and averaged envelope signals provided additional explanation of one calculated COFrms value. Envelopes of dynamic coefficient of friction enabled easier determination of different periods during sliding, which were further related to wear mechanisms

Microindentation of Polymethyl Methacrylate (PMMA) Based Bone Cement

Characterization of polymethyl methacrylate (PMMA) based bone cement subjected to cyclical loading using microindentation technique is presented in this paper. Indentation technique represents flexible mechanical testing due to its simplicity, minimal specimen preparation and short time needed for tests. The mechanical response of bone cement samples was studied. Realised microindentation enabled determination of the indentation testing hardness HIT and indentation modulus EIT of the observed bone cement. Analysis of optical photographs of the imprints showed that this technique can be effectively used for characterization of bone cements

Tribometry of Materials for Bioengineering Applications

Development of materials for biomedical implants (metals, polymers, ceramics and composites) is directly determined by characteristics and nature of the tissue, organs and systems that are being replaced or supplemented. Modern material investigations at micro- and nano- level enable introspection into new aspects of material behaviour and offer possibilities to significantly improve systems in use, from different aspects, such as improvement of manufacturing technologies or surface technologies modifications. Biomaterial investigations from a tribology point of view offer contribution to testing realised in this area, especially with use of novel devices for research in area of nanotribology

Cost optimization of additive manufacturing in wood industry

Software packages for 3D design and additive manufacturing (AM) technologies, initially known as rapid prototyping (RP) have emerged during the last years, as a cutting edge solutions for custom prototyping. These new tools and technologies lower the design costs, but also allow rapid creation of fully functional components. This paper describes the FDM and 3DP rapid prototyping technologies that were used to create elements and tools in the wood industry field. Total costs of manufacturing related to the fabrication of sample elements and tools are analysed. One of the main recognised issues of wider application of rapid prototyping technologies is their still very high costs related to all production aspects, starting with a lack of available materials, material cost, up to high cost of available commercial equipment, usually focused only on specific solutions and limited range of materials. Generally, AM costs can be divided into the group of fixed costs and variable ones. This paper deals with the optimization of the production costs of fabricated elements in case of small-scale production, and optimization of variable costs (processing and post-processing, costs of enforcement, and material costs)

Application of Contemporary Information Technologies in Nanotribometry

Relevant and timely information is of crucial importance in scientific investigations and understanding of the phenomena should be precise and explicit. Among other, phases of scientific investigations comprise data acquisition and their structuring into database and data warehouse, followed by their analysis in order to find laws and patterns and comparison with similar data. These activities are aimed at data to become information and for information to grow into knowledge and to further use that knowledge to formulate decisions and to anticipate future events and possibilities. However, simple analysis of information and responses to what already happened are not any longer satisfactory enough. Therefore, proactive approach is needed, that is technologies, skills and tools are needed that will assist in rapid decision making and forecasting. The paper presents architectures for data acquisition, developed databases and reporting, as well as, contemporary information technologies used for tribological investigations in area of nanotribometry

Friction Coefficient of UHMWPE During Dry Reciprocating Sliding

This paper deals with the friction coefficient behaviour during dry reciprocating sliding of UHMWPE in contact with alumina (Al2O3), within a range of velocities typical for hip implants. Five values of normal force (100 - 1000 mN) and three values of sliding speed (4 - 12 mm/s) have been observed. Real time diagrams of the friction coefficient as a function of the sliding cycles were recorded for each test. Dynamic friction coefficient curves exhibited rather uniform behavior for all test conditions. Somewhat larger values of friction coefficient could be observed during the running-in period in case of low loads (100 - 250 mN) and the lowest velocity (4 mm/s). In case of high loads and speeds, friction coefficient reached steady state values shortly after the beginning of the test

Wear Behaviour of Ti6al4v Alloy Against Al2o3 under Linear Reciprocating Sliding

Tribological behaviour of four different heat-treated Ti6Al4V alloys, during linear reciprocating sliding against alumina, on the microscale was investigated. Experiments were carried out for dry sliding and in the Ringer solution, over a range of loads (100-1000 mN) and speeds (4-12 mm/s). The wear mechanisms were investigated based on observations of worn surfaces. Specific wear rates for tested Ti6Al4V alloy were of order of 10(-7)-10(-4) mm(3)/N m. The lowest wear factor (order of 10(-7) mm(3)/N m) was observed for the Ti6Al4V annealed for I h at 750 degrees C in Ar atmosphere and then cooled down to room temperature in the furnace, tested in the Ringer solution. Load dependence of the wear factor exhibited transition characteristics. Wear mechanism has changed with change of load. The Ringer solution lowered wear factor for all tested conditions