Автор: Costas Passialis
Статии
- STRUCTURE AND PROPERTIES OF FIR (ABIES BORISII – REGIS MATTF.) AND SPRUCE (PICEA EXCELSA LINK) AND THEIR INFLUENCE ON WOΟD IMPREGNABILITY
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Резюме
Spruce and fir wood is important for Greek and Bulgarian forestry and wood industry. Durability of spruce and fir mature heartwood is low and both species are refractory to impregnation - spruce wood is poorly or not permeable, while fir wood is poorly to moderately permeable. The low permeability and the resistance of fir and spruce wood to impregnation are attributed to its specific anatomical – characteristics and properties. This work presents the structural characteristics and properties, summarises those anatomical characteristics which are related to impregnation processes and looks for new methods to improve fir and spruce wood permeability. Surface drilling of wood by laser beams might improve their permeability to preservatives and widen the uses of fir and spruce in exterior conditions.
Ключови думи: spruce, fir, wood structure, wood properties, permeability
- AN APPLICATION OF A LASER DRILLING TECHNIQUE TO FIR AND SPRUCE WOOD SPECIMENS TO IMPROVE THEIR PERMEABILITY*
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Резюме
In this work, the application of a laser drilling technique on fir (Abies borisii regis) and spruce (Picea excelsa) wood and a new approach of improvement the wood permeability is investigated. This technique is focusing on increasing the permeability of wood after surface drilling by a high power laser source. The research was involving the establishment of an effective drilling pattern protocol, which will not substantially affect the mechanical strength of wood and to improve its permeability. All lateral surfaces of the wood specimens, 2 × 2 cm in cross section and 34 cm long, were drilled by laser to a depth of 4 mm (1/5 of specimen thickness) with two drilling patterns (distance between holes 10 × 10 mm and 10 × 20 mm). Preliminary results showed that laser drilling is a promising method for improvement of wood permeability without significant effect on its mechanical strength, and this is very important for an effective treatment of the refractory to impregnation fir and spruce wood.
Ключови думи: laser drilling, fir/spruce wood, permeability, wood impregnation
- EFFECTS OF LASER DRILLING ON MECHANICAL PROPERTIES AND IMPREGNABILITY OF FIR AND SPRUCE WOOD*
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Резюме
Fir (Abies borisii regis) and spruce (Picea excelsa) wood specimens, 2 × 2 cm in cross section and 34 cm long, were prepared with true radial and tangential surfaces. All lateral surfaces of the specimens were drilled by laser to a depth of 4 mm (1/5 of specimen thickness) with two drilling patterns (distance between holes 1 × 1 cm and 1 × 2 cm). ). After drilling, the mechanical strength of wood (MOE, MOR, axial compression, toughness) was determined and compared with non-drilled controls. MOE was not affected by the laser drilling, MOR was significantly increased, axial compression was increased and toughness was decreased but not significantly. The overall results imply that strength properties do not decline by the laser drilling. Furthermore, wood specimens were impregnated with rape oil and CCB preservatives by applying vacuum (0.6 mmHg) and pressure (1,5 bars) for 15 minutes and 30 minutes, respectively. The results showed that both drilling patterns improved the retention and penetration of preservatives in fir and spruce wood specimens and, thus, are encouraging for further evaluating the drilling effects on the liquid permeability of these refractory to impregnation species. This effect was more pronounced in fir than in spruce wood.
Ключови думи: fir/spruce wood, laser drilling, mechanical strength, impregnability, retention, penetration