During the past few decades, special attention has been devoted to developing modern instruments and methods of monitoring the tribomechanical characteristics of technical systems. Today, various physical, chemical and tribological methods are used in tribomechanical systems diagnosis. Scientific experience in technical system exploitation and maintenance has shown that the most effective way to predict failure is based on parameters that are reliable indicators of wear. Analysis of oil samples, which contain particles due to the wear process, enables an evaluation of the tribology condition of the system in the early phases of its use. This paper deals with tribological tests that are part of the oil analysis and are used to access the condition of the system. Furthermore, the results of experimental research on the tribological characteristics of the oil sampled from engines and gear transmissions of the vehicles (Mercedes O 345, PUCH 300GD and PINZGAUER 710M) are shown. All of these road vehicle were in regular use by the Serbian armed forces. The performed research has revealed some significant changes in the tribological characteristics of oil for engine and gear transmission lubrication.. These changes directly depend on the condition of the entire engine and transmission elements, i.e. depend on their functional characteristics. The presented method of oil analysis should contribute to an early detection of failures due to friction and wear processes in vehicle engines and reduce the need for preventive maintenance.

An investigation of new PROTAC 500 armour steel was conducted. Three plates were heat treated to different states. One was quenched, the second and third were quenched and low temperature tempered at 220 and 280 °C for 3 hours. A tensile test, hardness measurements, and an instrumented Charpy test were performed. Metallographic was performed by optical microscopy (OM). Ballistic resistances of all three steel plates were measured. The behaviour of steel was tested using armour piercing projectiles 7.62×39 mm API BZ (former soviet designation for Armor Piercing Incendiary bullet). The best results were obtained in quenched state.

Abstract:The most common chemical's spills in typical transportation accidents are those with petroleum products such as diesel fuel, the consequence of which is an extensive pollution of the soil. In order to plan properly fuel recovery from the soil, it is important to gain information about the soil depth which may be affected by pollutant and to predict the pollutant concentration in different soil layers. This study deals with the impact of basic atmospheric conditions, i.e. air temperature and humidity on the diesel fuel migration through the soil. The diesel fuel was spilled into columns (L = 30 cm; D = 4.6 cm) fi lled with sandy and clay soil samples, and its concentrations at various depths were measured after 11 days under various air temperature (20 and 40°C) and relative humidity (30-100%) conditions. The effects observed were explained by understanding physical processes, such as fuel evaporation, diffusion and adsorption on soil grains. The increase in temperature results in higher fuel evaporation loss and its faster vertical migration. The relative humidity effect is less pronounced but more complex, and it depends much on the soil type.

Pure manganese coatings were prepared on the steel (AISI 4340) electrode by a non-conventional electrodeposition method, in the presence of 8 mol dm -3 of urea as a plating additive. The influence of urea on the electrodeposition of Mn was investigated by cyclic voltammetry. The morphology of the coatings was studied by scanning electron microscopy (SEM), and their elemental composition by energy dispersive X-ray spectrometry (EDS). The results showed that the presence of urea in the solution increased the current efficiency for metal reduction for around 20%, and depending on the applied deposition potential, urea may act either as a complexing agent or through the adsorption mechanism. Moreover, urea improves the characteristics of Mn deposits, i.e. their adhesiveness, porosity, compactness, and appearance. Except for oxygen, as part of the Mn corrosion product at the coating surface, no carbon or nitrogen incorporation was detected in the deposits by EDS.Keywords: urea; electrodeposition; Mn coating; morphology ЕЛЕКТРОДЕПОЗИЦИЈА НА МАНГАН ОД ЕЛЕКТРОЛИТ БОГАТ СО УРЕАПриготвени е филм од чист манган врз челична (AISI 4340) електрода со конвенционален метод на електродепозиција во присуство на 8 mol dm -3 уреа како адитив. Влијанието на уреата врз електродепозицијата на Mn беше испитувано со циклична волтаметрија. Морфологијата на филмот беше студирана со скенирачка електронска микроскопија (SEM), а елементарниот состав со енергетски дисперзивна спектрометрија со Х-зраци (EDS). Резултатите покажаа дека присуството на уреа во растворот ја зголемува ефикасноста на струјата со намалување на металот за околу 20% и во зависност од потенцијалот на депозиција уреата може да дејствува или како комплексирачко средство или преку атсорпционен механизам. Исто така, уреата ги подобрува карактеристиките на депозитите на Mn, т.е. нивната атхезивност, порозност, компактност и изглед. Освен кислород како дел од корозивниот продукт на Mn на површината на филмот, со EDS не беа детектирани инкорпорирани депозити на јаглерод или азот.

Dr Mladen Vuruna, potpukovnik, dipl. in`. Vojna akademija -Odsek logistike, Beograd profesor dr Du{an Antonovi} dipl. in`. Tehnolo{ko-metalur{ki fakultet, Beograd Rezime: U radu su prikazane osnovne fizi~ko-hemijske karakteristike dizel goriva i zemlji{ta. Obja{njena je migracija izlivenog naftnog zaga|iva~a kroz vertikalni profil zemlji{ta. U eksperimentalnom delu ispitivane su koncentracije dizel goriva i relativne koncentracije n-alkana u povr{inskim slojevima peska, u koje gorivo dospeva kao posledica akcidentnog izlivanja. Utvr|eno je da se koncentracije dizel goriva menjaju sa vremenom nakon izlivanja u svim ispitivanim slojevima. Tako|e, utvr|eno je da se dizel gorivo, kao potencijalni zaga|i-va~, u prvih {est nedelja, uglavnom, zadr`ava u povr{inskom sloju dubine 30 cm, a obja{njene su i mogu}nosti sanacije zaga|enog zemlji{ta. Klju~ne re~i: dizel gorivo, zemlji{te, koncentracija izlivenog goriva, relativne koncentracije n-alkana, tehnike ~i{}enja. Summary:The basic physical and chemical properties of both diesel fuel and soil have been given in this article and oil pollutants migration through vertical soil profile have been explained as well. In the experimental part of the paper both the concentrations of diesel fuel and relative concentrations of n-alkynes spilled in sandy soil by accident have been investigated. It has been proven that the concentrations of diesel fuel have changed in all layers of soil depending on the time after spill. Diesel fuel as possible pollutant has been retained 30 cm deep in sandy soil during six weeks after spill. Finally, cleanup techniques of polluted soil have been explained.