Wyniki wyszukiwania - BazTech

1

Pool Boiling Heat Transfer from Rough and Microstructure Coated Surfaces

Orman Łukasz J., Orman Katarzyna, Wojton Iwona

Rocznik Ochrona Środowiska

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2020

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Tom 22, cz. 1

514--525

EN

The paper presents the test results of pool boiling heat transfer on the rough surface and the surface covered with capillary – porous microstructure. The porous layer is made of copper fibers sintered in the reduction atmosphere. The volumetric porosity amounted to 68%, while its height 1 mm. Distilled water and ethyl alcohol were used as the working fluids. The experiments have been carried out under the atmospheric pressure. Enhancement of heat transfer in relation to the smooth reference surface has been recorded especially for the low range of superheats, which might be related to the density of active nucleation sites. Experimental results have been compared with selected models of boiling available in literature.

PL

Artykuł przedstawia wyniki badań wymiany ciepła przy wrzeniu na powierzchniach chropowatych i z porowatym pokryciem metalowo-włóknistym. Mikrostruktura porowata została wykonana z włókien miedzianych spiekanych w atmosferze redukcyjnej. Porowatość objętościowa wynosi 68%, a wysokość warstwy 1 mm. Badania prowadzono dla wody destylowanej i alkoholu etylowego jako cieczy wrzących pod ciśnieniem atmosferycznym. Zaobserwowano intensyfikację wymiany ciepła w porównaniu do powierzchni gładkiej, szczególnie w zakresie małych przegrzań, co może być związane z gęstością aktywnych centrów nukleacji. Wyniki badań eksperymentalnych porównano z wybranymi modelami wrzenia dla danych powierzchni.

2

SEM and EDS Characterization of Porous Coatings Obtained On Titaniumby Plasma Electrolytic Oxidation in Electrolyte Containing Concentrated Phosphoric Acid with Zinc Nitrate

Rokosz K., Hryniewicz T., Pietrzak K., Malorny W.

Advances in Materials Science

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2017

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Vol. 17, nr 2(52)

41--54

EN

The SEM and EDS results of porous coatings formed on pure titanium by Plasma Electrolytic Oxidation (Micro Arc Oxidation) under DC regime of voltage in the electrolytes containing of 500 g zinc nitrate Zn(NO3)2·6H2O in 1000 mL of concentrated phosphoric acid H3PO4 at three voltages, i.e. 450 V, 550 V, 650 V for 3 minutes, are presented. The PEO coatings with pores, which have different shapes and the diameters, consist mainly of phosphorus, titanium and zinc. The maximum of zinc-to-phosphorus (Zn/P) ratio was found for treatment at 650 V and it equals 0.43 (wt%) | 0.20 (at%), while the minimum of that coefficient was recorded for the voltage of 450 V and equaling 0.26 (wt%) | 0.12 (at%). Performed studies have shown a possible way to form the porous coatings enriched with zinc by Plasma Electrolytic Oxidation in electrolyte containing concentrated phosphoric acid H3PO4 with zinc nitrate Zn(NO3)2·6H2O.

3

Fabrication and characterisation of porous, calcium enriched coatings on titanium after plasma electrolytic oxidation under DC regime

Rokosz K., Hryniewicz T., Pietrzak K., Sadlak P., Valíček J.

Advances in Materials Science

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2017

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Vol. 17, nr 4(54)

55--67

EN

The purpose of this work is to produce and characterize (chemical composition and roughness parameters) porous coatings enriched in calcium and phosphorus on the titanium (CP Titanium Grade 2) by plasma electrolytic oxidation. As an electrolyte, a mixture of phosphoric acid H3PO4 and calcium nitrate Ca(NO3)2·4H2O was used. Based on obtained EDS and roughness results of PEO coatings, the effect of PEO voltages on the chemical composition and surface roughness of porous coatings was determined. With voltage increasing from 450 V to 650 V, the calcium in PEO coatings obtained in freshly prepared electrolyte was also found to increase. In addition, the Ca/P ratio increased linearly with voltage increasing according to the formula Ca/P = 0.035·U+0.176 (by wt%) and Ca/P = 0.03·U+0.13 (by at%). It was also noticed that the surface roughness increases with the voltage increasing, what is related to the change in coating porosity, i.e. the higher is the surface roughness, the bigger are pores sizes obtained.

4

Charakterystyka porowatych powłok otrzymanych na niobie i stopie Ti-Nb-Zr (TNZ) w procesie elektrolitycznego utleniania plazmowego (PEO)

Rokosz K., Hryniewicz T.

Mechanik

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2015

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R. 88, nr 12CD1

15--18

PL

Elektrolityczne utlenianie plazmowe (POE) zastosowano do biomateriałów metalowych, takich jak niob i stop Ti-Nb-Zr (TNZ). Obróbkę prowadzono w elektrolicie kwasu H3PO4 z dodatkiem azotanu miedzi. Otrzymane porowate powłoki badano z użyciem SEM/EDX. Badania uzyskanych powłok wykazały, że są one wzbogacone w jony miedzi (ponad 3,5 %mas.), podczas gdy Cu/P oraz Cu/(P+osnowa) wynosiły odpowiednio 0,2 i 0,07. Taka charakterystyka sprzyja poprawie biokompatybilności badanego biomateriału.

EN

The Niobium and Titanium-Niobium-Zirconium (TNZ) alloy biomaterials were treated by Plasma Electrolytic Oxidation (PEO) in view of getting porous surface layers. For the PEO process, a special set up was built to perform the experiments in the electrolyte composed of concentrated H3PO4, with an addition of copper II nitrate. The surface layers were studied by means of SEM and EDS methods to reveal the effects of porosity and compositions. It was found one may create porous coatings on niobium and on TNZ alloy, enriched with copper ions. Over 3.5 wt% content of copper, with Cu/P and Cu/(P+Matrix) ratios equaling to 0.2 and 0.07, respectively, may assure a better biocompatibility of the biomaterials.

5

Graphene based porous coatings with antibacterial and antithrombogenous function - Materials and design

Major R., Sanak M., Mzyk A., Lipinska L., Kot M., Lacki P., Bruckert F., Major B.

Archives of Civil and Mechanical Engineering

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2014

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Vol. 14, no. 4

540--549

EN

The studies considered graphene-based biomaterials dedicated for cardiovascular therapy. Reduced graphene oxide flakes were introduced into the porous structure of the polyelectrolyte based coatings. TEM analysis showed the presence of graphene flakes arranged parallel to the substrate surface, firmly connected to the porous coating. Biomaterials were subjected to a comprehensive diagnosis of the biological and material properties. The material behavior was simulated using finite element method. The coatings were deposited using layer by layer method. Mechanical analysis was done using Berkovich indenter geometry. They confirmed theoretical FEA based calculations, it was observed the coating stiffness incensement under the influence of introduced particles of graphene. The endanger of the bacteriology film formation was verified based on the E-coli and Staphylo coccus bacteria. Blood–material interaction was examined in the dynamic flow conditions. Bacteriological analysis showed reduced presence of bacteria after contact with the surface with introduced graphene flakes. Dynamic analyzes on blood showed high activation of the coagulation, strong platelets consumption and a strong immune response. It is caused by sharp edge of the single plane of the graphene flake.

6

Computer aided evaluation of poroaccessibility of porous coatings outer layer on intra-osseous implants

Uklejewski R., Winiecki M., Radomski W.

Engineering of Biomaterials

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2011

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Vol. 14, no. 109-111 spec. iss.

42--43

EN

The poroaccessibility of intra-osseous implant coating is the ability of the porous coating outer layer to accommodate the ingrowing bone tissue filling its pore space and effective new bone formation mineralizing in the pores to form biomechanically functional bone - implant fixation. The poroaccessibility determines the functional features of intra-osseous implant porous coating which are called its structural-osteoinductive properties [6, 8]. The structural-osteoinductive properties can be characterized by the set of three-dimensional parameters of poroaccessibility describing the functional properties of microgeometry of implant porous coatings: the effective volumetric porosity φ Vef , the index of the porous coating space capacity VPM, the representative surface porosity φ Srep, the representative pores size pSrep, the representative angle of the poroaccessibility Ωrep and the bone-implant interface adhesive surface enlargement index ψ [3,7,1]. The original method of stereometric evaluation of the microstructural properties of intra-osseous implants porous coatings by means of the parameters of poroaccessibility [4] is based the 3D roughness profilometry and was preliminary verified during experimental tests performed on the representative examples of porous coated femoral stems and acetabular cups of various hip endoprostheses [2,5,9]. In this paper we present the possibilities of computer aiding for evaluation of the poroaccessibility of porous coating outer layer of intra-osseous implants illustrated by the measurement data from the experimental tests performed on porous coated components of various hip endoprostheses. The computer aided evaluation of the microstructure of implant porous coatings can be realized b y t he authoring application software PoroAccess_1. 0 elaborated for our purposes in our research team in Java programming language. The screen of the application software is presented in FIG. 1. The PoroAccess_1.0 software lets to perform the dynamic analysis of the surface porosity φS in function of the pores depth pd which is showed as the map of porosity situated on the right side of the screen (see FIG. 1). The application software imports results from the series of contact profilometry measurements as the 2D matrices in ASC II format and calculates the values of the poroaccessibility parameters of porous coating outer layer according to the mathematical formulas given in [3,11]. The applications software also has the module enabling 3D visualization of measured region of porous coating outer layer as the isometric plot. The presented methodology provides the characterization of the effective part of porous coating – its outer layer, which is full of pores open for penetrating bone tissue with the diameter of many macro pores surpassing 100 μm. Such size of pores, according to clinical research [1], is beneficial for bone tissue to grow into the coating, so the pore space of the porous coating outer layer participates in creating biomechanically functional bone-porous implant fixation. The set of poroaccessibility parameters characterizes some major aspects of porous coating outer layer features. The parameters describe spatial (φVef, φSrep), volumetric (VPM), hybrid (pdef, ΩMMrep) and some functional (physicochemical) properties of implant porous coatings outer layer, e.g. enhancement of the adhesive properties (ψ), which can be indirectly interpreted in the aspect of its structural-osteoinductive properties [10]. The presented methodology of characterization of implant porous coatings with use of the poroaccessibility parameters is going to be applied as a specific tool in research on designing porous coatings with functionally graded pore distribution and designed poroaccessibility. Nowadays, the best potential to manufacture implant porous coatings with designed poroaccessibility have Direct Metal Manufacturing (DMM) technologies like Selective Laser Sintering / Melting (SLS/M) or Electron Beam Melting (EBM), so the next stage of this research is the investigation on the possibilities to manufacture the porous coating with designed poroaccessibility in one of DMM technologies. The biostructural evaluation of the manufactured in DMM technologies porous coatings together with its biological evaluation in NHOst cultures is expected to provide more information about the representative features of the microstructure of the porous coatings and allow to evaluate the most advantageous poroaccessibility of their pore spaces for potential bone tissue ingrowth to be verified in further in vivo test on animal models.

7

Energy saving using heat exchangers covered with porous coatings

Wójcik T. M.

Structure and Environment

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2010

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Vol. 2. no. 3

35-39

EN

Exploitation of technical devices is always related to the energy consumption. Thus, if more efficient heat exchangers are used as part of mechanical systems, it is possible to save energy. The paper presents possible ways of producing more efficient heat transfer surfaces working under the nucleate boiling mode. When porous coverings are used, significant reduction of temperature differences is noticed at the same heat flux. It leads to higher energy efficiency.

8

Badania mikrostruktury porowatych pokryć modelowych implantów dokostnych

Uklejewski R., Winiecki M., Rogala P.

Engineering of Biomaterials

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2009

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Vol. 12, no. 89-91

112--114

9

Experimental Investigations on the Structural-Osteoinductive Properties of Porous Coatings on Orthopaedic Implants

Uklejewski R., Winiecki M., Mielniczuk J., Auguściński A., Rogala P.

Machine Dynamics Problems

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2006

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Vol. 30, No. 4

171-180

EN

The adaptive bone tissue ingrowth into the pore space of a porous coating on orthopaedic implants is influenced by the structural-osteoinductive properties of this coating. The effective bone tissue ingrowth determines the proper fixation of the porous implant in its bony surroundings. The adequate evaluation of the structural-adaptive compatibility of bone-implant interface can be performed on the basis of the two-phase poroelastic biomechanical model of bone tissue and of implant porous coatings with the set of original parameters characterizing the poroaccessibility of implant porous coatings: the effective volumetric porosity φVef, the index of the porous coating space capacity VPM, the effective pore depth ρdef, the representative surface porosity φSrep, the representative pore size ρSrep, the representative angle of the poroaccessibility Ωrep, the index of the enlargement of the adhesive surface of bone-implant interface Ψ, which is proposed in (Mielniczuk et al., 2006; Winiecki et al., 2006; Uklejewski et al., 2005a and 2005b; Winiecki, 2006) to the biostructural evaluation of the porous coated orthopedic implants. This paper presents the results of experimental investigations of the microgeometrical properties of implants porous coatings made with contact profile measurement on the representative examples of endoprostheses stems.