The present study discusses the influence of engine oils on the tribological parameters of sliding couples with laser borided surface layer. The borided layer was formed on specimens made from AISI 5045 steel by laser remelting of a surface layer coated with amorphous boron. The sliding friction and wear process was carried out on the pairs with AISI 5045 steel and SAE-48 bearing alloys which were lubricated with 5W-40 and 15W-40 engine oils. The investigation showed significant differences in the friction coefficient and temperature in the tested pairs with the laser borided surface layer. In the couples lubricated with 5W-40 engine oil, the tested parameter of friction was higher than in the couples lubricated with 15W-40 engine oil. The couples lubricated with 5W-40 engine oil showed more intensive wear of SAE-48 bearing alloy in contact with the laser borided surface layer than the pairs lubricated with 15W-40 engine oil. The laser borided surface layer used in friction pairs leads to the destruction of the lubricating properties of engine oils and reduces its resistance to scuffing.
The article assesses two provinces of the south-eastern Poland, i.e. Lublin Province and Podkarpackie, taking into account the number of accidents, persons injured and the persons who caused the accident. In addition, the most common causes of such negative traffic incidents, i.e. speeding or weather conditions, are listed. For better evaluation of the safety on the roads of Lubelszczyzna and Podkarpacie, the road accident rate in the said provinces was compared with the national average. Also, the actions taken to improve the traffic safety on Polish roads were presented.
This article describes factors that affect the demand for services offered at the gas stations in Poland. Main types of gas stations that operate within the country are listed and characterised. It is also determined which gas stations are the most popular among the customers and which services rendered are the most important for the consumers. To decide which facilities providing technical re-sources for automotive sector in terms of distribution of, among others, gasoline, diesel fuel and biofuels are best, major oil and gas corporations, i.e. PKN ORLEN, BP and Grupa LOTOS are analysed. The main criteria of assessment of these corporations is information that allows to compare the number of their gas stations, prices of liquid fuel and LP gas and additional services, i.e. fuel cards.
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