Istraživanje i procjena zaostalih naprezanja u plinski naštrcanim NiCrBSi slojevima

For thermally sprayed coatings, beside good wear and corrosion resistance there is also a need for a good coating/substrate adhesion, reduced porosity and reduced level of residual stresses. Residual stresses that occur in the substrate/coating system are very significant because their relaxation can cause different coating failures. In this paper, different approaches to investigation of residual stresses in thermally sprayed coatings, have been presented. An analytical model (authors Tsui and Clyne) was used to estimate the distribution of residual stresses in flame sprayed and fused NiCrBSi coatings. These data can be used as input data for the numerical model.Za toplinski naštrcane slojeve, uz dobru otpornost slojeva na trošenje i koroziju, postoje i zahtjevi za dobrom prionjivosti sloja na podlogu,smanjenom poroznosti i smanjenom razinom zaostalih naprezanja. Zaostala naprezanja koja se pojavljuju u sustavu podloga/naštrcani sloj, osobito su važna, jer se njihovom relaksacijom mogu pojaviti razna oštećenja sloja. U ovome radu prikazani su pristupi istraživanju zaostalih naprezanja u toplinski naštrcanim slojevima, te je na osnovi analitičkog modela (autori Tsui i Clyne) procijenjena raspodjela zaostalih naprezanja za NiCrBSi slojeve nanesene postupkom plinskog naštrcavanja praha s utaljivanjem. Ovi podaci mogu se koristiti kao ulazni podaci za numerički model

Novi podaci o rasprostranjenosti riba Phoxinellus alepidotus (Heckel, 1843) i Aulopyge huegelii (Heckel, 1841)

This paper presents recent found localities for species Phoxinellus alepidotus (Heckel, 1843) and Aulopyge huegelii (Heckel, 1841) in Bosnia and Herzegovina. Found localities are at the highest altitude ever detected and the locality for the species A. huegelii Hec. is the first ever for the Black Sea basin. The species P. alepidotus Hec. and A. huegelii Hec. were probably unintentionally introduced to the Šatorsko Lake during the 1970s and 1980s while other species of trout were being introduced.U radu se navode nedavno otkriveni lokaliteti za vrste Phoxinellus alepidotus (Heckel, 1843) i Aulopyge huegelii (Heckel, 1841) u Bosni i Hercegovini. Ti lokaliteti nalaze se na najvećoj nadmorskoj visini dosada, a lokalitet za A. huegelii je prvi za crnomorsko slivno područje. Vrste P. alepidotus Hec. i A. huegelii Hec. vjerojatno su slučajno unesene u Šatorsko jezero tijekom sedamdesetih i osamdesetih godina 20. st., za vrijeme unošenja drugih vrsta pastrva

Another contribution to the location of an ancient cultic site in the village of Priluka near Livno and attempts to reconstruct the monument

Još jedan slučajan nalaz u blizini zaselka Vašarovine u selu Priluka bio je povodom da se ponovno osvrnemo na ovaj važan i kompleksan, ali sustavno neistraživan lokalitet s područja Livanjskoga polja. Ulomak zabata s dijelom reljefnoga prikaza razmatra se ikonografski, stilski i funkcionalno. Veže se uz kult Genija, odnosno Libera, upućujući na organizirano rimsko naselje i kultno-hodočasničko središte u Vašarovinama, u kojima je najvjerojatnije djelovala i prepoznatljiva klesarska radionica.Another chance find near the hamlet of Vašarovine in the village of Priluka prompted another examination of this important and complex, yet systematically unexplored locality in Livno field. The fragment of a pediment with a partial relief image is examined with a particular focus on its iconography, style and function. It is associated with the cult of Genius or Liber, indicating the existence an organised Roman settlement and a cult/pilgrimage centre in Vašarovine, where a recognisable masonry workshop was also active

Analysis of weld joints made of titanium alloy GRADE 2 produced by electron beam welding

Selected properties of welded joints of 2 mm thick titanium alloy Grade 2 produced by different welding parameters of electron beam welding were investigated. The visual inspection, macro and micro analysis, tensile strength test and microhardness measurements were performed. Samples manufactured by appropriate welding parameters had no internal defects, heat-affected zone (HAZ) was narrow and transformation from α phase to β phase was observed in this area. The failure occurred in the base metal during tensile test, while maximum ultimate tensile strength reached 454,3 MPa

Analysis of interconnection between physical and protective properties of two-component epoxy primer

This paper presents the research into protective properties of two-component epoxy primer obtained by measurements of the notch corrosion and by testing of the gloss as a physical property. In order to obtain different values of measured response, the first experiment was done by applying the primer in various amounts of the dry film thickness, while the second experiment was based on combining various contents of anti-corrosion pigment. Analysis of the obtained research results proved the interconnection between the two observed properties. It was confirmed that the obtained results were inversely proportional for both experiments. Protective properties of coating could be assessed by measuring the gloss value, which is simpler and faster than measuring the notch corrosion

Analysis of plated layer’s effects on the structure resistance to corrosion

This paper presents the laboratory testing of protective effects that the plated layer had on the structure resistance to corrosion by using the weighing method, i.e. the method of mass loss. The described procedure refers to preparation of samples, their exposure to aggressive atmosphere of the salt chamber and analysis of obtained results. According to the properties of the base material and its reduced stability in the experimental conditions, it is confirmed that the use of plated layer was required to improve the structure resistance to corrosion and to protect the base material

Axial light emission and Ar metastable densities in a parallel plate dc micro discharge in steady state and transient regimes

Axial emission profiles in a parallel plate dc micro discharge (feedgas: argon; discharge gap d=1mm; pressure p=10Torr) were studied by means of time resolved imaging with a fast ICCD camera. Additionally, volt-ampere (V-A) characteristics were recorded and Ar* metastable densities were measured by tunable diode laser absorption spectroscopy (TDLAS). Axial emission profiles in the steady state regime are similar to corresponding profiles in standard size discharges (d=1cm, p=1Torr). For some discharge conditions relaxation oscillations are present when the micro discharge switches periodically between low current Townsend-like mode and normal glow. At the same time the axial emission profile shows transient behavior, starting with peak distribution at the anode, which gradually moves towards the cathode during the normal glow. The development of argon metastable densities highly correlates with the oscillating discharge current. Gas temperatures in the low current Townsend-like mode (T= 320-400K) and the high current glow mode (T=469-526K) were determined by the broadening of the recorded spectral profiles as a function of the discharge current.Comment: submitted to Plasma Sources Sci. Techno