Hagyományos bevonatok teljesítmény mutatói

Varnished wooden surfaces got widespread in Europe in the 17 th century; their golden era lasted till the 1930s, when the easier applicable nitrocellulose based lacquers gradually took their place in the furniture industry. Nowadays besides furniture restoration the natural surface treating materials are newly rediscovered, polished furniture is considered fashionable and prestigious. Lacquers based on synthetic resins are relatively well documented with regard to their behavior during service, whilst few results exist about polishes this regard. Since almost every workshop used different formula for their polishes, this study investigates and compares those with significantly different composition, in order to determine the difference – if there is any – between their gloss, color brightening effect and adhesion thus allowing a purposeful choice for the users. Most of the authors dealing with surface treatment of wood describe the different characteristics such adhesion of the lacquer layer, gloss of the surface etc. being strongly dependent from the wood species the layer was applied on, accordingly our measurements were performed on two wood species: walnut ( Juglans regia L.) and cherry (Prunus subg. Cerasus) . Four different polish formulas were applied: french polish and three types of english polish. Haze and gloss, pencil hardness, shock resistance, adhesion and resistance against chemical impacts was tested and evaluated in comparison with the performance of nitro cellulose lacquers too. Key words: polish recipes, english polish, french polish, gloss, pencil hardness, varnish adhesion, shock resistance, resistance against chemicals

COMPARATIVE ANALYSIS OF STATIC AND DYNAMIC MOE OF PANNÓNIA POPLAR TIMBER FROM DIFFERENT PLANTATIONS

The aim of this study has been to investigate the suitability of Pannónia poplar (Populus × euramericana cv. Pannónia) timber for structural purposes. Static and dynamic modulus of elasticity (MOE) has been determined on samples of 4 different Hungarian plantation origins. The results of the dynamic test showed the same range as the static test, showing a good correlation of the two measurements. As result it can be stated that the domestic Hungarian Pannónia poplar species have in average 11000 N.mm-2 modulus of elasticity. This exceeds considerably the threshold limit value (7000 N.mm-2) necessary for structural applications according to Eurocode 5. Therefore Pannonia poplar is suitable for structural applications, and are a good alternative of the widely used coniferous species in construction sector

Improving sustainability of mortar by wood-ash and Nano-SiO2

Cement production charges the environment with CO2 pollution and exhausts natural stocks of limestone and clay. Cement was partially replaced with Wood Ash (WA), and nano-SiO2 (NS) was added to balance the strength loss. Mortar specimens were prepared by replacing the cement with WA up to 20 %, 30 %, 40 %, and 50 %, using constant-flow mortar. The flexural and compressive strength results indicated that although adding 40 % of WA reduced the mortar's strength, it still remained in an acceptable zone (higher than 20 MPa). The addition of 2.5 % NS recovered the strength loss caused by replacing cement with 40 % WA

Measurements of the Load-bearing Structural Aspects of Pannónia Poplar from Sites in Western Transdanubia, Hungary

This study summarises the test results of Pannónia poplar (Populus × euramericana cv. Pannónia) originating from three plantation sites in Győr-Moson-Sopron County in the Western Transdanubia region of Hungary: Újrónafő 11G, Győr 540B, and Kapuvár 35A. The research primarily aimed to clarify the characteristics of radial growth depending on the plantation site and to predict the selected physical and mechanical properties of the xylem. Measuring the time-of-flight (TOF) in trees was performed with a non-destructive test technique using a “Fakopp” TreeSonic device. The stress wave velocity (SWV) values calculated from TOF data are significant in estimating the dynamic modulus of elasticity (MOE) of the xylem and, therefore, in the prediction of timber suitability for structural applications. During the on-site measurements, 50 trees – as random samples from every site – were investigated to determine the diameter at breast height (DBH) and the stress wave velocity in sapwood parallel to the grain. In addition to the non-destructive measurements, the laboratory analysis of the xylem from harvested logs (three logs per site, random sample) was also performed to determine the radial growth rate and density. The one-way ANOVA results revealed significant differences in SWV values between certain plantation groups. The difference between the average values of young and old plantations is 136.8 m/s, which is a significant difference. Similar findings occurred for the middle-aged and old plantation trees. The average values of the young and the middle-aged trees can be considered the same at the 0.05 level of significance. We also established that the trees in the young (22 years old) plantation site, Újrónafő 11G, planted with the closest spacing (3 m × 4 m), had the lowest average diameter of breast height naturally and showed the highest average value of SWV. Nevertheless, the sap- and heartwood samples from this plantation site had the highest average density values in a normal climate; therefore, the highest dynamic modulus of elasticity of the xylem can be expected in logs originating from this plantation site

Bondability of Beech Wood with One-component Polyurethane Structural Adhesive

Abstract The bondability of beech (Fagus sylvatica L.) wood with a one-component polyurethane (1K PUR) structural (load-bearing) adhesive has been investigated at the Simonyi Károly Faculty at the University of West Hungary. Our trial is considered a preliminary investigation in order to set the convenient parameters of bonding for the structural gluing of beech wood. Wood samples were characterized by their oven dry density, and the surfaces to be bonded were characterized by their surface roughness and surface tension after machining. Based on our measurements, we have made a suggestion on the value of the ensemble of open time, applied quantity and pressure, pressing time, and surface preparation/surface roughness parameters which result in good bonding and a shear strength higher than 10 N/mm2. Furthermore, we investigated the penetration of the adhesive into the surface and state that one-sided adhesive application results in differing levels of penetration. In order to check the suitability of beech wood for glued laminated timber production, further investigations according to EN standards are necessary. Based upon the considerations noted above, delamination tests are already under evaluation.</jats:p

Tölgy fafelületek néhány paraméterének vizsgálata megmunkálás után

Faanyagok ragasztásakor és felületkezelésekor nagyon fontos szerep jut a nedvesítésnek. A faanyag nedvesíthetősége egyenes arányban áll a felületi feszültséggel, azaz minél nagyobb az anyag felületi feszültsége a folyadékhoz képest, annál jobban nedvesíti a folyadék a felületet. Jelen tanulmányban a fa felületi érdességének nedvesítésre, felületi feszültségre gyakorolt hatását vizsgáltuk, meghatáro - zott, a gyakorlat számára is releváns érdesség tartományban. A kocsánytalan tölgy ( Quercus petraea ) alapanyagot három különböző szemcsefinomságú (60, 80, 100) csiszolópapírral csiszoltunk, majd a mintatesteken felületi érdesség és felületi feszültség méréseket végeztünk. Míg a vizsgált felületek érdességében szignifikáns különbségeket tapasztaltunk, addig a felületi feszültség értékei egymáshoz igen közel állnak, a mért adatokban nem volt szignifikáns különbség. Feltételezzük, hogy az érdesség - nek ebben a tartományában az 5 μl űrtartalmú vízcsepp a lokális érdesség durva felszínű viszonyai kö - zepette túl nagy ahhoz, hogy 2-3-4 egymás mellé sorolódó érdesség csúcs adta érdességet kimutasson