Acta Polytechnica. 2017, vol. 57, no. 2
http://hdl.handle.net/10467/72664
2024-03-28T18:15:32ZSURFACE CONSOLIDATION OF WALL PAINTINGS USING LIME NANO-SUSPENSIONS
http://hdl.handle.net/10467/72706
SURFACE CONSOLIDATION OF WALL PAINTINGS USING LIME NANO-SUSPENSIONS
Vojtěchovský , Jan
Within the field of the conservation of historical and cultural monuments, lime nanosuspensions are still a relatively new and unexplored material. This study examines their effect on the consolidation of architectural surfaces and, consequently, on wall paintings. Previous experiments showed that considerably deteriorated materials may not be adequately strengthened using only lime nano-suspensions. Therefore, the effects of their admixtures and gradual applications with silicic acid esters were examined. For verification, a simulation of a deteriorated lime-based paint layer was created on panels of plaster. The results of the consolidation were subsequently studied using objective (peeling test, water absorption capacity test, measuring colour changes using a mobile spectrophotometer) and subjective methods (comparison of visual changes to a set standard and by testing cohesion using a cotton swab). The microstructure of a consolidated paint layer was studied with a scanning electron microscopy. Tests proved that with either individual lime-alcoholic suspensions or with successive applications and mixtures of silicic acid esters it is feasible to achieve good consolidation results, whilst the alkoxysilane content of the agent indisputably increases the consolidating effect of these materials.
2017-01-01T00:00:00ZMODIFICATION OF POWDER MATERIAL BY COMPACTION PROCESSING
http://hdl.handle.net/10467/72705
MODIFICATION OF POWDER MATERIAL BY COMPACTION PROCESSING
Peciar , Peter; Macho , Oliver; Eckert , Maroš; Kabát , Juraj; Gabrišová , Ľudmila; Kotora , Peter; Fekete , Roman; Peciar , Marián
There are different criteria for assessing the appropriateness of an agglomeration technology in the deployment processing of dry, fine and dirty dust burdening in the communal and working environment. Besides the benefit of the environment components, the agglomeration technology offers the possibility of re-processing the material as the primary raw material within a wide range of industries. Preliminary tests have shown that the compressed material remains in the memory from the previous compression. For returning the already processed material into a primary production, it is essential that it is reformed without the need for additional materials, a requirement that can be problematic. This article deals with the modification of a powder material (powder dust from the manufacture of friction components) and the investigation of its properties before and after the compaction processing.
2017-01-01T00:00:00ZTHE IMPACT OF SELECTED PROCESSES AND TECHNOLOGICAL PARAMETERS ON THE GEOMETRY OF THE WELD POOL WHEN WELDING IN SHIELS GAS ATMOSPHERE
http://hdl.handle.net/10467/72704
THE IMPACT OF SELECTED PROCESSES AND TECHNOLOGICAL PARAMETERS ON THE GEOMETRY OF THE WELD POOL WHEN WELDING IN SHIELS GAS ATMOSPHERE
Bradáč , Josef; Moravec , Jaromír
This paper is focused on welding with a consumable electrode in a gas shield atmosphere and its main aim is to show the influence of selected processes and technological parameters on the geometry of the weld pool in terms of theoretical and experimental views. For this purpose, the parametric areas defined by the change of the welding current and welding rate were determined. Apart from the influence of these parametric areas, the influence of other technological input variables, including the wire diameter and preheating temperature, was also studied. The experimentally obtained geometric data of the weld pool can be used for technological welding procedures WPS and especially for simulation calculations to obtain a more accurate numerical model of the heat source. This makes it possible to get accurate simulation results and to better understand the impact of other variables that influence the welding process. This all helps to the optimization of the welding process for several applications.
2017-01-01T00:00:00ZCYCLIC TEMPERATURE LOADING RESIDUAL FLEXURAL STRENGHT OF REFRACTORY SLABS
http://hdl.handle.net/10467/72703
CYCLIC TEMPERATURE LOADING RESIDUAL FLEXURAL STRENGHT OF REFRACTORY SLABS
Holčapek , Ondřej; Reiterman , Pavel; Konvalinka , Petr
This paper describes the effect of cyclic elevated temperature loading on refractory slabs made from high performance, fibre reinforced cement composite. Slabs were produced from aluminous cement-based composites, reinforced by different dosages of basalt fibres. The composite investigated in this study had self-compacting characteristics. The slabs used were exposed to different thermal loading – 600 °C, 1000 °C, six times applied 600 °C and 1000 °C. Then, flexural strength was investigated in all groups of slabs, including group reference slabs with no thermal loading. The results show that the appropriate combination of aluminous cement, natural basalt aggregate, fine filler and basalt fibres in dosage 1.00% of volume is able to successfully resist to cyclic temperature loading. Tensile strength in bending of these slabs (after cyclic temperature loading at 600 °C) achieved 6.0 MPa. It was demonstrated that it is possible to use this composite for high extensive conditions in real industrial conditions.
2017-01-01T00:00:00Z