Utjecaj poprečne brzine na nepravilnosti površine dobivene abrazivnim rezanjem vodenim mlazom

The paper deals with the calculation of the optimal traverse speed for diff erent types of materials, which is very important for predication, imaginings and dimensioning of technological factors and selection of the materials with the aim to increase of surface quality at abrasive waterjet cutting (AWJ) technology. The surface irregularities of the experimental used materials AISI 304, AISI 309 have been measured by non-contact shadow method. New empirically compiled equations of the infl uence of the traverse speed on tensometrical state of cut, deformation resistance of material and surface roughness Ra are at AWJ cutting available.Rad se bavi proračunom optimalne brzine rezanja za različite vrste materijala, što je vrlo važno za predikaciju, osmišljanje i dimenzioniranje tehnoloških čimbenika i izbor materijala s ciljem da se poveća kvaliteta površine reza tehnologijom abrazivnim vodenim mlazom (AWJ). Površinske nepravilnosti eksperimentalno korištenih materijala AISI 304, AISI 309 su mjerene bezkontaktnom metodom sjene. Dobivena je nova empirijska jednadžbe utjecaja brzine na tenzometrijsko stanje rezne površine, deformacijsku otpornost materijala i površinsku hrapavost Ra kod AWJ rezanja

Klasifikacija tehničkih materijala prema klasama obradivosti kod hidroabrazivnog rezanja

This paper presents the major cutting knowledge, the opinion data and the results of actual theoretic parameters solutions and the current results, estimated by contemporary needs of hydro abrasive cutting technology. Here is a newly opened and discussed question of current data terminology disunity in the area of metrology topography surfaces of cutting walls created by abrasive waterjet.U radu su prezentirana temeljna znanja, razmišljanja i rezultati teorijskih rješenja vezano uz trenutne procijenjene suvremene potrebe za hidroabrazivnom tehnologijom rezanja. Ovdje je i ponovo otvoreno pitanje trenutne terminologije u području mjeriteljstva topografi je površina dobivenih rezanjem abrazivnim vodenim mlazom

Analiza topografije površina titanove legure nakon rezanja vodenim mlazom pomoću spektralne analize

Experimental study of a titan grade 2 surface topography prepared by abrasive waterjet cutting is performed using methods of the spectral analysis. Topographic data are acquired by means of the optical profilometr MicroProf®FRT. Estimation of the areal power spectral density of the studied surface is carried out using the periodogram method combined with the Welch´s method. Attention is paid to a structure of the areal power spectral density, which is characterized by means of the angular power spectral density. This structure of the areal spectral density is linked to the fi ne texture of the surface studied.Eksperimentalna studija površine titana klase 2 dobivene abrazivnim rezanjem vodenim mlazom je provedena korištenjem metode spektralne analize. Topografski su podaci prikupljeni pomoću optičkog profi lometra MicroProf®FRT. Procjena površinske snage spektralne gustoće je provedena periodogram metodom u kombinaciji sa Welch metodom. Pozornost je posvećena površinskoj snazi spektralne gustoće koja je karakterizirana pomoću kutnih spektara gustoće snage. Struktura površinskog spektra gustoće je povezana sa istraživanom fi nom teksturom površine

Disordered Gd6_{6}UO12−δ_{12-δ} with the cation antisite defects prepared by a combined mechanochemical−thermal method

The synthesis of the rhombohedral Gd$_{6}$UO$_{12-δ}$ is reported via mechanochemical processing of stoichiometric Gd$_{2}$O$_{3}$/UO$_{2}$ mixtures and their subsequent annealing. Rietveld refinement of XRD data reveals that the as-prepared material exhibits a remarkable degree of cation antisite disorder and oxygen deficiency. The simulations of intensities of the selected XRD superlattice reflections are performed for limiting states of Gd$_{6}$UO$_{12-δ}$ with its most extreme degrees of the cation antisite disorder. On the basis of the estimated bond lengths it can be stated that distorted geometry of structural units in the material is a consequence of its relatively large oxygen deficiency

A sustainable reaction process for phase pure LiFeSi2O6 with goethite as an iron source

Lithium-iron methasilicate (LiFeSi$_{2}$O$_{6}$, LFS), a member of clinopyroxene family, is an attractive compound for its multiferroic properties and applicability in energy-related devices. Conventional preparative method requires heating at elevated temperatures for long periods of time, with inevitable severe grain growth. We demonstrate that α-FeO(OH) (goethite) is superior as an iron source toward phase pure LFS over conventional hematite, α-Fe$_{2}$O$_{3}$. The exact phase purity, i.e., no trace of iron containing reactant, is confirmed in the goethite-derived LFS by 57Fe Mössbauer spectroscopy. The grain growth of LFS during heating is suppressed to keep its crystallite size of 120 nm. Higher reactivity of goethite in comparison with hematite is mainly attributed to the dehydration of goethite, which in our case was accelerated by Li$_{2}$O. Related reaction mechanisms with the possible product pre-nucleation during mechanical activation are also mentioned. The magnetic properties of goethite-derived LFS are equivalent to those prepared via a laborious solid-state route. Thus, the presented preparative method offers a more sustainable route than conventional processing, and thus enables practical application of LFS

Nanostructure and Magnetic Anomaly of Mechanosynthesized Ce1-xYxO2-δ (x ≤ 0.3) Solid Solutions

Electromagnetic properties of complex oxide solid solutions containing Ce and Y attract increasing interests due to their high application potential. Their properties are known to be dependent on many factors including grain size and crystal defects. Here we focus on unique features of nanocrystalline Ce1-xYxO2-δ (x ≤ 0.3) solid solutions prepared via a mechanosynthesis. Mechanically activated CeO2-δ and mechanosynthesized Ce1-xYxO2-δ exhibit room-temperature ferromagnetism. The saturation magnetization reaches maximum for the Ce0.9Y0.1O2-δ solid solution. XPS and Raman spectra show that Ce4+ ions are partially reduced to Ce3+, with simultaneous introduction of oxygen vacancies accumulated on surface of the solid solutions. An analysis of the experimental magnetization data and the determination of both the spin state and the concentration of magnetic carriers revealed that a small part of the Ce3+ spins (<1%) is responsible for the magnetic state of the Ce1-xYxO2-δ system. Existence of clusters with a short-range antiferromagnetic order is also suspected. © 2020 Elsevier LtdThe present work is supported by the APVV (project 19-0526 ), EUREKA (project E!9982 ) and the VEGA (project 2/0055/19 ). A. Ye. thanks the State Assignment (Theme “Magnit” No. АААА-А18-118020290129-5) for financial support. H.K., K.L.S. and M.S. are grateful to the National Scholarship Program of Slovakia ( SAIA, n. o.). V.Š. acknowledges the support by the DFG (project SE 1407/4-2 )

Ecotoxicity Study of New Composite Materials Based on Epoxy Matrix DER-331 Filled with Biocides Used for Industrial Applications

The impact of fillers in the epoxy oligomer on the test culture of the marine ecosystem was investigated. The content of additive—biocides—was selected based on the complex research using STAT-GRAPHICS® Centurion XVI. The ecotoxicity of composite surfaces was determined in model systems using methods which are standard in eco-microbiology. The microorganism was identified by studying morphological, cultural, biochemical, and antigenic properties. Studies of the structure and the microrelief of the surfaces of composite materials were conducted using scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy. Based on comprehensive research, it was established that the composition of oxytetracycline with content of q = 1.5 wt% and nanosilver with a content of q = 0.075 wt% per 100 wt% of the DER-331 oligomer and 10 parts by the mass of the TETA hardener ensures the formation of a porous nano-heterogeneous structure of the coating, which leads to the acceleration of the release of silver ions from the surface of the polymer. The rational content of the complex additives of biocides ensures adhesion to the cell wall of bacteria with subsequent penetration into it and subsequent change to the cell membrane, its death, and, therefore, the suppression of the fouling process of metal structures

Concept of optimization for technology of hydroabrasive cutting of materials

This paper aims to clarify the abrasive waterjet technology, particularly in terms of surface creation. It provides new insight into the deformation process caused by the abrasive waterjet and possibilites of using the surface topography for optimization of the process

Comparation and analysis of material roughness getted possesion of abrasive water jet

Material surface getted possession of abrasive water jet analysis by not contact optical method, results evaluation of material surface measuring by the contact method