Wyniki wyszukiwania - BazTech

1

Bond strength of concrete-filled hollow section with modified fibrous foamed concrete

Khairuddin S. A. A., Rahman N. A., Jamaluddin N., Jaini Z. M., Elamin A., Rum R. H. M.

Archives of Civil Engineering

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2020

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Vol. 66, nr 3

97--108

EN

The concrete-filled section of columns has been widely in construction used due to its structural elements. As a result, the usage of composite columns has recently increased all over the world. However, using foamed concrete alone does not result in much improvements in strength. Therefore, this paper examines the use of foamed concrete containing fibre to improve the strength of composite columns. Specifically, this study aims to determine the bond strength of concrete-filled hollow section (CFHS) with modified fibrous foamed concrete. Two types of fibre are used in this work, namely, steel fibre and polypropylene fibre, with rice husk ash (RHA) as a sand replacement to improve the compressive strength of foamed concrete. The CFHS with modified fibrous foamed concrete is tested by using the push-out method, and the results show that CFHS with steel fibre has a highest bond strength.

2

Bond strength of orthodontic adhesives to dry and saliva-moistened enamel a comparative in vitro study

Stefański T., Kloc-Ptaszna A., Postek-Stefańska L.

Archives of Materials Science and Engineering

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2019

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Vol. 96, nr 2

79--84

EN

Purpose: To compare the bond strengths of six different dental adhesives to dry and salivamoistened enamel. Design/methodology/approach: One hundred twenty stainless steel brackets were bonded to human mandibular third molars with six materials: Enlight LC® (Ormco Corp), Grengloo® (Ormco Corp), Light Bond® (Reliance Orthodontic Products), Charisma® (Heraeus Kulzer), SmartBond® (Gestenco), and Transbond XT® with MIP® primer (3M Unitek). One half of the specimens in each group (n=10) was bonded to dry enamel, while the other half to saliva-moistened enamel. Bond strength testing was performed with a wire loop loading technique after 30-min incubation in artificial saliva. Failure mode was evaluated using adhesive remaining index (ARI). Findings: No significant differences in bond strength to dry enamel were noted for all composite materials (p>0.05). SmartBond exhibited significantly greater bond strength to moistened enamel (7.10 ± 1.47 MPa) and comparable with other composite materials to dry enamel. Composite materials demonstrated significantly reduced bond strength to saliva-moistened enamel (p<0.001), except for Transbond MIP, whose bond strength was not significantly decreased by saliva contamination (p=0.089). There was not statistically significant difference between bond strength of SmartBond and Transbond to saliva contaminated enamel. A higher incidence of cohesive failures was noted for all materials. Research limitations/implications: Composite light-cured materials provide adequate bond strength to dry enamel. Cyanoacrylate adhesive provides sufficient bond strength only under moist conditions. Transbond XT+MIP has sufficient bond strength to either dry or saliva-moistened enamel. Practical implications: The study evaluated the bonding strength of orthodontic brackets, which is a critical parameter in orthodontics, especially in situations that do not allow for proper isolation from saliva, such as bonding to impacted teeth following surgical exposure. Originality/value: Bond strengths evaluated with loop loading technique in different study environments would help the orthodontist to choose the most effective adhesive for the specific clinical situation.

3

On the bonding strength of FE-based self-fluxing alloy coating deposited by different methods on the steel substrate

Feldshtein E., Kardapolava M., Dyachenko O.

International Journal of Applied Mechanics and Engineering

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2018

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Vol. 23, no. 2

355--364

EN

In the present paper, the bonding strength of Fe-based self-fluxing alloy coating deposited by plasma spraying, gluing and laser remelting and alloying on the steel substrate have been investigated. When flame melting, a globular structure is formed. Against the background of the solid solution carbide-boride phases are clearly distinguishable, between which the Fe–Fe2B and Fe–FeB eutectic colonies are situated. Laser remelting leads to the formation of metastable structures, reinforced with dendrites, consisting of alloyed Fe-α and Fe-γ. At the low laser beam speeds the coating is melted completely with the formation of a cast structure with the dendrites. When the laser beam speed is increased, the dendritic structure gets fragmented. Structures of coatings alloyed with B4C and remelted by the laser beam vary with the increase of the spot speed. The bonding strength of coating without subsequent remelting decreases by 4–5 times in comparison with remelted. The bonding strength of the reinforced glue coating has adhesive and adhesive-cohesive character. When the load increases in the coating, microcracks develop, which gradually spread to the center of the bonding surface. For plasma coatings after laser remelting without additional alloying, the maximum bonding strength is observed with the minimum laser beam speed. With increasing the laser beam speed it decreases almost 1.5 times. In glue coatings reinforced with B4C particulates by laser remelting, the bonding strength is lower by 1.2–1.4 times in comparison with plasma coating.

4

The role of mechanical, chemical and physical bonds in metal-ceramic bond strength

Czepułkowska W., Wołowiec-Korecka E., Klimek L.

Archives of Materials Science and Engineering

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2018

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Vol. 92, nr 1

5--14

EN

Purpose: A review regarding the mechanisms of metal-ceramic join is presented. Design/methodology/approach: The impact of the air-abrasion parameters on the mechanical bond strength of the ceramic crowns was discussed. The presence of opaque on the chemical bond was analysed. Research of the influence of the difference in the coefficient of thermal expansion values on the metal-ceramic bond was included. The methods of testing the bond strength were analysed. Findings: The metal substructure-dental ceramic bond strength is affected by all types of bond. In bond strength, 3-point bending test and shear test are mainly used. Created samples simulate the ceramic crowns veneered on one side. The role of physical bond on ceramic crowns veneered around metal substructure is unknown. Research limitations/implications: The prosthetic restorations with the ceramic surrounding whole the metal substructure are commonly used. The impact of shrinkage in the cylindrical deposition of the ceramic on metal substructure should be analysed. Practical implications: Numerical analysis and FEM simulation can be helpful in the analysis of the physical bond between the metal substructure and the dental ceramic around it. Originality/value: The impact of the type of the bond to metal-ceramic bond strength is presented, taking into account the cognitive gap in the influence of the coefficient of thermal expansion on the cylindrical placement of ceramic on the substructure.

5

Values of the binding force of common seabuckthorn with a plant

Sadowska U., Żabiński A., Mudryk K.

Agricultural Engineering

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2014

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Vol. 18, No. 4

213--220

EN

The aim of the study was to determine the effect of selected operating parameters of the two types of orchard sprayers on vertical distribution (expressed as spray percentage share in 50-cm segments) and quantitative changes in the vertical distribution of spray measured on the vertical separator of drops. The study included measurements of the vertical distribution of spray for two different ways of nozzles setting, two types of nozzles and two fan rotation speeds. The vertical distribution of spray depended significantly on spray emission system, the configuration and the type of nozzles and in the slightest degree on the fan rotation speed. The smallest share of liquid fell on the edge segments (≤ 5.22%) and the largest on the middle ones – 29.33%. The change in the configuration of nozzles significantly affected the change in the spray vertical distribution (by the spray displacement between the 50-cm segments). The greatest changes in the vertical distribution of spray – as affected by nozzle configuration change – was observed for the sprayer with the horizontal spray emission with maximum change in one segment of 14.0% (an average of 7 segments: 5.38%).

PL

Rokitnik zwyczajny to krzewiasty gatunek rośliny z rodziny oliwkowatych o owocach zasobnych w składniki aktywne biologicznie. Jest wciąż mało rozpowszechniony w Polsce, co związane jest w dużym stopniu z trudnościami zbioru niewielkich i gęsto osadzonych owoców na ciernistych gałęziach. Celem pracy było wyznaczenie i porównanie wartości sił wiązania owoców z pędem dla dwóch odmian rokitnika zwyczajnego, Botaniczeskaja i Augustinka. Materiał badań pochodził z własnej plantacji doświadczalnej. Badania prowadzono na maszynie wytrzymałościowej MTS zrywając owoce z dwóch stref krzewów, środkowej i dolnej. Stwierdzono zależność statystyczną wartości sił wiązania owoców poszczególnych odmian od lat badań, a także umiejscowienia owoców na krzewie. Najsłabiej związane były owoce odmiany Botaniczeskaja zbierane w 2012 roku, charakteryzujące się średnią wartością siły wiązania wynoszącą 1,65 N. Mniejsze wartości sił wiązania dla tej odmiany obserwowano w przypadku owoców znajdujących się w dolnej części krzewu.

6

Ocena wytrzymałości mechanicznej klejów ortodontycznych w testach bezpośrednich

Pawlus B., Dyszkiewicz A., Špidlen M.

Engineering of Biomaterials

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2012

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Vol. 15, no. 115

38--44

PL

Celem pracy było stworzenie stanowiska pomiarowego do porównania i oceny właściwości wytrzymałościowych klejów wykorzystywanych do mocowania zamków ortodontycznych na zębach. Utworzono stanowiska pomiarowe dla badań przeprowadzanych na maszynie wytrzymałościowej z tensometrem oporowym, miernikiem wagowym oraz z serwomechanizmem, umożliwiającej przeprowadzenie statycznych prób wytrzymałościowych. Autorski system pomiarowy umożliwia pozaustrojową ocenę maksymalnych naprężeń ścinających, rozciągających i skręcających, działających na zamek ortodontyczny, zespolony z powierzchnią zęba. Badaniom próbnym poddano następujące materiały łączące: Transbond XT 3M, Light Bond Reliance, Enlight Ormco. Sporządzono 90 próbek z usuniętymi zębami przedtrzonowy- mi ludzkimi. Utworzono losowo 3 grupy po 10 próbek. Każda grupa została przypisana do odpowiedniej metody badawczej. Badania przeprowadzono in vitro w temperaturze 24 stopni Celsjusza w godzinę po przytwierdzeniu zamka. Dla próby ścinania najwyższe wartości średnich naprężeń granicznych wykazał Transbond XT. Najniższe wartości średnie ustalono dla Enlight Ormco. Dla próby rozciągania najwyższe wartości średnich naprężeń granicznych wykazał Enlight Ormco. Najniższe wartości średnie ustalono dla Transbond XT 3M. Najwyższe średnie wartości dla momentu skręcającego, przy którym doszło do zerwania materiału zarejestrowano dla Light Bond Reliance. Najniższe wartości średnie wykazał Enlight Ormco. Wyniki testów tensometrycznych wykazywały w badanych materiałach zbieżny trend największej odporności na działanie sił skręcających, mniejszy na działanie sił ścinających i najmniejszy na wpływ sił rozciągających. Rozbicie wypadkowej na poszczególne składowe naprężenia odzwierciedla naturalne zachowania wytrzymałościowe materiału łączącego z zamkami ortodontycznymi.

EN

New materials for fastening teeth braces enabled more common use of the fixed appliances. Binding strength is being transferred to the teeth by orthodontic brackets fitted with linking material. A common problem is brackets peeling off. Information about the material strength is essential for adhesive selection. The aim of the study was to develop measurement system for comparison and estimation of binding properties of the bond used for orthodontic appliances. Measurement system allows to evaluate maximum shear, tension and torsion stress. The following materials were tested in the study: 3M Transbond XT, Reliance Light Bond, Ormco Enlight. 90 samples of human premolars were made. Three groups of 10 samples were created. Each group was assigned to the particular method and to the adhesive test. The maximal and minimal values of average shear stress were demonstrated with Transbond XT and Ormco Enlight. Tension stress showed maximal mean values for Ormco Enlight, minimal for 3M Transbond XT. The maximal mean values of torsion were recorded for Reliance Light Bond, the minimal for Ormco Enlight. The results showed the greatest resistance convergent trend for torsion, less significant for shear and the least influence of tension forces. Components of the net force reflect the natural behavior of the orthodontic adhesives.

7

Wartości siły związania ziarniaków z osadką kłosową jęczmienia nago i okrytoziarnistego

Sadowska U.

Inżynieria Rolnicza

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2007

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R. 11, nr 9 (97)

197-202

PL

W pracy przedstawiono wyniki badań wielkości siły wiązania ziarniaków z osadką kłosową jęczmienia nagoziarnistego w porównaniu z okrytoziarnistym w zróżnicowanych gęstościach wysiewu: 200, 350 i 500 nasion na 1 m2. Materiał badawczy pozyskano ze ścisłego dwuczynnikowego doświadczenia polowego. Zastosowano nagoziarnistą odmianę Rastik, oraz tradycyjną okrytoziarnistą odmianę Bies charakteryzującą się podobnym tempem rozwoju. Na podstawie uzyskanych wyników stwierdzono, że odmianę nagoziarnistą cechuje mniejsza siła wiązania ziarniaków z osadką kłosową w porównaniu z oplewioną. Uzyskane wyniki siły wiązania ziarniaków z osadką kłosową skorelowano z wysokością niedomłotów zebranych po zbiorze kombajnowym. Otrzymano wysoki współczynnik korelacji dla tej zależności r = 0,94.

EN

The paper presents results of research on the value of force binding potatoes with ear rachis in gymnospermous barley, as compared to that in angiospermous barley, for diversified seeding densities: 200, 350 and 500 seeds per 1 m2. The test material was obtained through a precise twoelement field experiment. The following barley varieties were used: gymnospermous Rastik and conventional angiospermous Bies characterised by similar growth rate. Obtained results allowed to determine that gymnospermous variety is characterised by smaller force binding potatoes with ear rachis, as compared to the other one. Obtained results concerning the force binding potatoes with ear rachis were correlated with the amount of not threshed material picked after combine harvester crop. The researchers obtained high correlation coefficient for this relation: r = 0.94.

8

Influence of nanofillers on the impregnating varnishes properties

Górnicka B., Mazurek B., Zawadzka J.

Prace Naukowe Instytutu Podstaw Elektrotechniki i Elektrotechnologii Politechniki Wrocławskiej. Konferencje

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2003

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Vol. 39, nr 14

69-74

EN

The authors focus on preparation and characterization of nanofilled impregnating varnishes for modern electrical motor applications. The processing methodology for dispersion of nanofiller (surface modified layered silicates) in a few kinds solventless varnishes based on polyester and polyestreimide resins have been developed. 2-3% of nanofiller were incorporated while keeping the technological properties of impregnating varnishes at appropriate level. Mechanical properties of nanofilled varnishes as well as theirs thermal stability has been studied. Significant improvements of bond strength and thermal endurance of nanofilled varnishes have been observed. Improving of varnish properties by incorporating of nanofiller is more ecological solution then using of different types of expensive reactive monomers.