International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The paper presents the results of research aimed at determining selected tribological properties of PVD nanocoatings. PVD nanocoating of the 4th generation duplex nACRo4 was applied to the surface of shaped parts of molds and cores for high-pressure aluminium casting. The surfaces were laser textured with a random texture. The tribological properties of the coating were determined by measuring the friction coefficient using the Pin on Disc method at a temperature of 300 °C. Confocal microscopy was used to determine the parameters of the microgeometry of surfaces with random texture topography. The aim of this surface treatment was to analyse the adhesion effect of commercially used ones of lubricants in the technology of treatment of shaped parts of molds when casting aluminium alloys under high pressure on machines with a cold filling chamber. By checking the integrity of textured surfaces with deposited with the duplex PVD coating of the 4th generation nACRo4, no damage to the integrity of the deposited material was detected PVD coating. Elements forming the PVD coating were detected on the surface by semiquantitative EDX microanalysis.

Modern vehicle braking systems mainly are based on deceleration of vehicle and tire slip control. Trends in improving vehicle braking performance give rise to a large variety of braking systems and control strategies. An anti -lock braking system is an electronic braking process control system, which greatly increases the ability of the driver and vehicle to avoid road accidents even during difficult braking conditions or circumstances. The load (number of passengers in the vehicle) which is transmitted to the road surface through the vehicle tires is an issue which directly affects the braking efficiency of the vehicle during stopping. The braking efficiency also depends on
the material of the road surface, climatic condition, road condition, vehicle speeds and tire condition.
The purpose of this paper is investigation the impact of the number of passengers in the vehicle during the braking process, respectively to determine the performance of the braking of vehicles equipped with modern mechatronic braking systems such as: Antilock Braking System, Electronic Braking System, Emergency Brake System and Electronic Brake-force Distribution System.
The braking performance of the vehicle was determined experimentally through the XL Meter device which was fixed on the windshield of the VW Polo vehicle. The tests were performed on asphalt roads for different speeds of 40, 60 and 80 km/h. The determination of the center of gravity of the vehicle and the reaction forces in the front and rear axles was performed through the devices in the Motor Vehicle Laboratory of the Faculty of Mechanical Engineering and the developed mathematical model for calculating static and dynamic reactions forces for the respective axes. The obtained results will help the traffic experts in the analysis of road accidents.

The paper presents the results of studies of tribological properties of the contact of the tool steel composition Fe-18W-4Cr-1,2V with the magnesium alloy AZ91D strengthened by submicron powder filling out of SiC and severe plastic deformation (SPD), namely equalchannel angular pressing (ECAP). It is stated that introduction of SiC powder filling to the magnesium alloy the friction coefficient on the moving frictional contact increases, the wear rate reduces. These tribotecnical characteristics are influenced by the size and volume of the particles of powder filling, normal loading force and slip rate. SPD of the initial material results in reduction of the adhesion constituent of the friction coefficient.

The paper presents results of research of the essential characteristics of two kinds of advanced coatings applied by HVOF technology. One studied coating: WB-WC-Co (60-30-10%) contains two types of hard particles (WC and WB), the second coating is ecofriendly alternative to the previously used WC-based coatings, called “green carbides” with the composition WC-FeCrAl (85-15%). In green carbides coating the heavy metals (Co, Ni, NiCr) forming the binding matrix in conventional wear-resistant coatings are replaced by more environmentally friendly matrix based on FeCrAl alloy. On the coatings was carried out: metallographic analysis, measurement of thickness, micro-hardness, adhesion, resistance to thermal cyclic loading and adhesive, abrasive and erosive wear resistance. There were also determined corrosion characteristics of the coatings in NaCl and SAR solutions.

Bulk forming is one of the most effective and efficient manufacturing processes. Mass production of many of the items without any defects has been possible because of the advancements in cold bulk forming. The characteristic of a lubricant, especially coefficient of friction influences the interfacial friction during the forming process. This friction causes defects and many difficulties and has to be kept within limits so the proper choice of lubrication is very important for the quality of the formed product. The influence of lubricant’s coefficient of friction on different mechanical and electrical properties of cold extruded material has been investigated and described in this paper by performing many different tests and measurements for mechanical properties and electrical conductivity of the formed material. Coefficients of friction for four different lubricants were first obtained by ring test, and then these lubricants were used in cold extrusion process. The obtained experimental results describing the effect of lubrication on material properties were presented in a form of diagrams and have shown that choice of lubrication could influence some material properties.

The paper presents the program and methodology of carrying out research on kinematic pair with pivoting friction. There was examined a node with pivoting friction in bearing concentrated connection flat surface-spherical bowl. During the research there were determined two types of characteristics – characteristic of friction moment as a function of load and experimentally designated characteristic of wear of the frictional kinematic pair. Both of the assigned characteristics are compared.

The paper presents the program and methodology of carrying out research on kinematic pair with pivoting friction. There was examined a node with pivoting friction in bearing concentrated connection flat surface-spherical bowl. During the research there were determined two types of characteristics – characteristic of friction moment as a function of load and experimentally designated characteristic of wear of the frictional kinematic pair. Both of the assigned characteristics are compared.

The influence of parameters of ultrasonic pressing on the mechanical and tribological properties of composite materials on the basis of polytetrafluoroethylene is considered. A new technology for the friction bearings production is proposed and its advantages are shown.

This paper presents values comparison of friction coefficient inside ball joints depending course given by the vehicle, period of exploitation and the vehicle brand. Friction coefficient were defined on the contact surface between steel ball joint pin and the ball joint seat made from plastic covered by PTFE. For the selected working pair of the elements comparison of friction coefficient in load function are done. The preform of the measurements methodology and the test bench are additional show in the paper.

This paper presents values comparison of friction coefficient inside ball joints depending course given by the vehicle, period of exploitation and the vehicle brand. Friction coefficient were defined on the contact surface between steel ball joint pin and the ball joint seat made from plastic covered by PTFE. For the selected working pair of the elements comparison of friction coefficient in load function are done. The preform of the measurements methodology and the test bench are additional show in the paper.

Bronzes type BrZhNA 12-7-1 (12% Fe, 7% Ni, 1% Al) form dendritic structure that consists of a maraging martensitic steel 03N15Yu1 mesh, which arms matrix given bronze with content Cu – base, 5-6% Ni and 1% Al. Dendrites can be strengthen by dispersion hardening. Mass transfer phenomena during crystallization and heat treatment in these bronzes were investigated. This bronze has elevated mechanical and technological properties, low friction coefficient and high wear resistance level during sliding friction.