Cavitation damages morphology of high-strength low-alloy steel

This paper presents the research into behaviour of HSLA steel affected by cavitation. The parent material (PM) and simulated heat-affected zone (SHAZ) were studied. Ultrasonic vibratory cavitation test was performed in laboratory conditions (by stationary specimen method). Scanning electron microscopy (SEM) was used to observe the variations in the surface morphology that occurred within different time intervals

Cressa cretica L. (Convolvulaceae) u flori Hrvatske

According to VISIANI (1826: XVIII–XIX) Cressa cretica was found in the area of Dalmatia around the middle of the 16th century by Luigi Anguillara. Since later explorers of the flora of Dalmatia did not confirm this finding it only has a historical significance. This thermo-cosmopolitan halophilous species from Convolvulaceae family was found in the salt marsh area of Blato by the Solaris hotels near Šibenik in June 1996. Observations that were made in period from 1997 to 2002 show that it is an annual plant with a short life cycle that continues in the summer period when the salt marsh area drains. It grows as a part of halophitic vegetation, mostly with the species Suaeda maritima, Salicornia europaea, Salsola soda, Limonium vulgare subsp. serotinum and Crypsis aculeata. With the exception of the locality of Blato by Solaris, Cressa cretica has not been found on any other locality in the wider area of Šibenik.Prema Visianiju (1826: XVIII–XIX) vrstu Cressa cretica sredinom 16. stoljeća navodi Luigi Anguillara za područje Dalmacije. Kasniji istraživači dalmatinske flore nisu potvrdili ovaj nalaz pa on ima samo povijesno značenje. Ova termokozmopolitska halofitna vrsta iz porodice Convolvulaceae prona|ena je u lipnju 1996. godine na slanom močvarnom području Blato, uz hotelsko naselje Solaris u blizini Šibenika. Promatranja u razdoblju 1997.–2002. pokazuju da se radi o jednogodišnjoj biljci s kratkim životnim ciklusom koji se odvija tijekom sušnog ljetnog razdoblja kada slano močvarno područje presušuje. Raste u sastavu halofilne vegetacije najčešće s vrstama Suaeda maritima, Salicornia europaea, Salsola soda, Limonium vulgare subsp. serotinum i Crypsis aculeata. Za sada nije pronađena na drugim lokalitetima na širem šibenskom području

Experimental and Numerical Evaluation of a Steamline Behaviour Using Local Approach

Results of the experimental and numerical comparative analysis of steamline pipes have been presented. New pipes and the pipes used for more than 117,000 hours at 540 °C under pressure of 42 bars have been simultaneously tested. This testing has been carried out because frequent failures of the equipment components exposed to elevated temperatures, such as steam pipelines, make it necessary to pay particular attention to the analysis of the materials used. The most frequent failures were those connected with occurrence of cracks, particularly expressed in case of steel 14MoV6 3. Local approach to fracture has been developed for complete understanding of fracture mechanism. This approach combines theoretical, experimental and numerical solution

Suitability of heat treatment for crack resistance of material in the connection part of heavy transporter for liquid slag

The post weld heat treatment (PWHT) was used to reduce the level of the residual stresses and increase of the crack resistance of the material in the connection part. The article presents the results of the residual stress measurements immediately after welding and after the stress relaxation by the PWHT

Suitability of heat treatment for crack resistance of material in the connection part of heavy transporter for liquid slag

The post weld heat treatment (PWHT) was used to reduce the level of the residual stresses and increase of the crack resistance of the material in the connection part. The article presents the results of the residual stress measurements immediately after welding and after the stress relaxation by the PWHT

Microstructural investigation of the heat-affected zone of simulated welded joint of P91 steel

In the process of testing real components exposed to elevated temperature, it is not possible to neglect cracks. The most significant cracks can be induced by welding, which is applied for joining of structural components. Pressure equipment in service is also exposed to high pressure and high stresses. Materials for their manufacturing are designed to resist high stress at elevated temperature, and to meet requirements regarding creep resistance. The objective of this study is to investigate microstructure of different regions of the heat affected zone in T/P91 steels by using thermal simulation instead of welding

Specifična absobcijska energija staklo-poliester kompozitne cijevi pod statičkim tlačnim opterećenjem

The experimental determination of energy of glass-polyester composite tubes static fracture is done. The tubes are of defined structure and known processes of fabrication. The aim was to determine the possibility of their usage as damping elements during impact. Two types of tubular samples with different diameters were tested until fracture under static (low speed) compressive loading. The applied forces and sample lengths were measured until complete destruction of samples. From the diagrams received directly from testing devices, certain energy values explained in the paper were determined.U radu je prikazano eksperimentalno određivanje statičke energije loma staklo-poliester kompozitnih cijevi poznate struktura materijala i postupka izrade. Cilj ispitivanja je bio odrediti mogućnost primjene ugradnje takvih cijevi u elemente za prigušivače udara. Pod djelovanjem spornog statičkog tlačnog opterećenja ispitivana su dva tipa cijevi različitih presjeka. Pri tom su mjerene primenjene sile i duljine uzoraka sve do potpunog loma cijevi. Na osnovu dobivenih dijagrama su izračunate vrijednosti specifičnih energija apsorpcije

Specific energy absorption capacity of glass-polyester composite tubes under static compressive loading

The experimental determination of energy of glass-polyester composite tubes static fracture is done. The tubes are of defined structure and known processes of fabrication. The aim was to determine the possibility of their usage as damping elements during impact. Two types of tubular samples with different diameters were tested until fracture under static (low speed) compressive loading. The applied forces and sample lengths were measured until complete destruction of samples. From the diagrams received directly from testing devices, certain energy values explained in the paper were determined

Effects of fluorination on the structure, magnetic and electrochemical properties of the P2-type NaxCoO2 powder

The main goal of this research has been to investigate for the first time the effects of fluorination on the crystal structure, magnetic, and electrochemical properties of the P2-type NaxCoO2 powder. Sodium cobalt oxide with a P2-type structure is synthesized by a modified solid-state reaction consisting of alternating processes of rapid heating up to 750 °C and rapid cooling to the room temperature. The obtained powder is fluorinated using a gas-solid reaction with NH4HF2 as fluorinating agent. Fluorination causes a decrease of sodium content in the parent phase with the concurrent formation of the minor phases of Na2CO3 and NaF. The structure of NaxCoO2 in both powders is refined in P63/mmc space group. The results of the Rietveld refinement combined with the findings from the XPS measurements confirm the Na0.76CoO2 and Na0.44CoO1.96F0.04 stoichiometries for the pristine and fluorinated powders, respectively, which indicates that 4 at.% of fluorine ions per formula unit are incorporated in the structure. Preliminary electrochemical investigations have revealed an improved charge/discharge performance. The influence of fluorination on morphology and magnetic properties has also been examined. © 2018 Elsevier B.V

Optimization of the flux values in multichannel ceramic membrane microfiltration of Baker`s yeast suspension

The objective of this work was to estimate the effects of the operating parameters on the baker's yeast microfiltration through multichannel ceramic membrane. The selected parameters were transmembrane pressure, suspension feed flow, and initial suspension concentration. In order to investigate the influence and interaction effects of these parameters on the microfiltration operation, two responses have been chosen: average permeate flux and flux decline. The Box-Behnken experimental design and response surface methodology was used for result processing and process optimization. According to the obtained results, the most important parameter influencing permeate flux during microfiltration is the initial suspension concentration. The maximum average flux value was achieved at an initial concentration of 0.1 g/L, pressure around 1.25 bars and a flow rate at 16 L/h. [Projekat Ministarstva nauke Republike Srbije, br. TR 31002