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Wyświetlanie 1-5 z 5
Tytuł:
Gaseous Atmosphere During Gas Forming Tendency Measurements of the Selected Protective Coatings for Sand Moulds
Autorzy:
Mocek, J.
Powiązania:
https://bibliotekanauki.pl/articles/2079824.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
gas forming
oxygen
hydrogen
carbon monoxide
protective coatings
gaz
tlen
wodór
tlenek węgla
powłoki ochronne
Opis:
Protective coatings have direct contacts with hot and liquid alloys. As the result of such contacts gases are emitted from coatings. Gas forming is a tendency of the tested material to emit gases under a temperature influence. In order to assess the gas forming tendency either direct or indirect methods are applied. In the hereby work, the measurements of the gas forming tendency were performed under laboratory conditions, by means of the developed indirect method. The research material constituted samples of six selected protective coatings dissolved either in alcohol or in water. These coatings are applied in sand moulds and cores for making cast iron castings. The assessment of their gas forming tendency was presented in relation to temperatures and heating times. The occurrence and changes of oxygen and hydrogen contents in gases outflowing from the measuring flask during tests, were measured by means of gas sensors. The process of the carbon monoxide (CO) emission during tests was also assessed. The following gas sensors were installed in flow-through micro chambers: for oxygen - lambda probe, for hydrogen – pellistor, for carbon monoxide - sensor (dedicated for CO) FIGARO TGS 822 TF. The results of direct CO measurements were recalculated according to the algorithm supplied by the producer of this sensor.
Źródło:
Archives of Foundry Engineering; 2021, 21, 3; 11-18
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Assessment of the Permeability of Selected Protective Coatings Used for Sand Moulds and Cores
Autorzy:
Jamrozowicz, Ł.
Siatko, A.
Powiązania:
https://bibliotekanauki.pl/articles/381009.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
permeability
protective coatings
coating viscosity
core
mold
przepuszczalność
powłoki ochronne
lepkość powłoki
rdzeń
forma
Opis:
The article presents the results of permeability measurements of a zirconium alcohol coating applied on moulds and cores. The introduction extensively discusses the reasons for the application of protective coatings, as well as their advantages and disadvantages. Also, the problems related to the application of protective coatings are presented i.e. limited permeability and thus the possibility of the presence of gas-originated defects in the casts. Next, the paper discusses the methods of measuring the permeability of protective coating proposed by Falęcki and Pacyniak. The study also presents an indirect permeability measurement method. For the investigations, zirconium alcohol coatings with the three conventional viscosities 10, 20 and 30s were used. The viscosity was determined by means of the Ford cup with the clearance of 4mm. The coatings were applied onto profiles of Φ 50x50 mm, made of moulding sand consisting of a sand matrix with the mean grain size of dL = 0,11, 17, 24, 31 and 34 mm and phenol-formaldehyde resin. The effect of the matrix grain size on the permeability of the sand with and without a coating was determined.
Źródło:
Archives of Foundry Engineering; 2020, 20, 1; 17-22
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of the Mould Material Coatings on the Microstructure of AlSi7Mg Alloy
Autorzy:
Dybowski, B.
Poloczek, Ł.
Jarosz, R.
Kiełbus, A.
Powiązania:
https://bibliotekanauki.pl/articles/383041.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
metallography
AlSi7Mg alloy
protective coatings
sand casting
metalografia
stop AlSi7Mg
powłoki ochronne
odlewy piaskowe
Opis:
Family of the aluminium alloys with silicon addition is an important group of non-ferrous casting alloys. They exhibit very good technological properties, especially castability. Aluminium alloys are known for their low density, which in connection with high mechanical properties and relatively low price create very good structural material. Magnesium addition to the Al-Si alloys enables their age-hardening, resulting in even better mechanical properties. However, formation of the microstructure of the alloy has to be precisely controlled to avoid formation of massive, brittle silicon crystal. Presence of large, platelet-like particles of silicon, dramatically decreases material mechanical properties. Second factor, which must be taken into consideration is casting porosity, which may significantly decrease fatigue life of the element. Many researches consider effect of modification or refining on the microstructure of the castings made from the Al-Si alloys. However there is lack of detailed investigation on the mould components influence on the microstructure. Such components may be protective coatings applied for the mould sand during the gravity casting of Al-Si alloys. Following paper presents results of the research on the influence of applied mould protective coatings on the microstructure of AlSi7Mg sand cast alloy. Five different protective coatings were applied. Macro observations, qualitative and quantitative microstructure evaluation of the AlSi7Mg alloy was conducted during the researches. Results revealed, that application of the coatings does not influence the size and distribution of the α- Al dendrites, however it influences size of Si particles in a significant way. It was revealed that application of water-based coatings affects the heat flow in the mould material-liquid alloy system, thus causing growth of silicon particles.
Źródło:
Archives of Foundry Engineering; 2015, 15, 1 spec.; 13-16
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Humidity Migration in Surface Layers of Sand Moulds During Processes of Penetration and Drying of Protective Coatings
Autorzy:
Jamrozowicz, Łukasz
Zych, Jerzy
Powiązania:
https://bibliotekanauki.pl/articles/2203936.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
surface layers
sand mould
porous medium
humidity migration
protective coatings
resistance measurement
warstwy powierzchniowe
formy piaskowe
migracja wilgoci
powłoki ochronne
pomiar rezystancji
Opis:
The results of investigations of humidity migration in near surface layers of sand mould during processes of penetration and drying of protective coatings are presented in the hereby paper. The process of the humidity exchanging between surroundings and moulding sands as porous materials, is widely described in the introduction. In addition, the humidity flow through porous materials, with dividing this process into stages in dependence of the humidity movement mechanism, is presented. Next the desorption process, it means the humidity removal from porous materials, was described. Elements of the drying process intensity as well as the water transport mechanisms at natural and artificial drying were explained. The innovative research stands for measuring resistance changes of porous media due to humidity migrations was applied in investigations. Aqueous zirconium coatings of two apparent viscosities 10s and 30s were used. Viscosity was determined by means of the Ford cup of a mesh clearance of 4mm. Coatings were deposited on cores made of the moulding sand containing sand matrix, of a mean grain size dL = 0.25 mm, and phenol-formaldehyde resin. Pairs of electrodes were placed in the core at depths: 2, 3, 4, 5, 8, 12 and 16 mm. Resistance measurements were performed in a continuous way. The course of the humidity migration process in the core surface layer after covering it by protective coating was determined during investigations. Investigations were performed in the room where the air temperature was: T = 22 oC but the air humidity was not controlled, as well as in the climatic chamber where the air temperature was: T =35 oC and humidity: H = 45%. During the research, it was shown that the process of penetration (sorption) of moisture into the moulding sand is a gradual process and that the moisture penetrates at least 16 mm into the sand. In the case of the drying (desorption) process, moisture from the near-surface layers of the moulding sand dries out much faster than moisture that has penetrated deeper into the sand.
Źródło:
Archives of Foundry Engineering; 2022, 22, 4; 72--78
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rola kształtu powierzchni formy w procesie wysychania wybranych powłok ochronnych
The Role of the Surface Shape of the Mould in the Process of Drying of Selected Protective Coatings
Autorzy:
Jamrozowicz, Ł.
Zych, J.
Kolczyk, J.
Wróblewski, D.
Powiązania:
https://bibliotekanauki.pl/articles/381974.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
forma piaskowa
powłoki ochronne
szybkość wysychania
technika grawimetryczna
sand mould
protective coatings
speed drying
gravimetric technique
Opis:
W artykule zaprezentowano wyniki badań szybkości schnięcia wybranych powłok ochronnych. Badaniom poddano powłokę wodną WC-R i alkoholową Zirkofluid 1219. Wyznaczono kinetykę wysychania powłok. Powłoki była nanoszono na rdzenie wykonane z masy o średniej wielkości ziarna osnowy dL= 0,24 mm. Ponadto wyznaczono szybkość wysychania powłok dla trzech ich lepkości umownych (11s; 20s; 30s). Lepkość powłok określono przy pomocy kubka „Forda”. Badania szybkości wysychania powłoki ochronnej prowadzono techniką grawimetryczną. Proces wysychanie mierzono w sposób ciągły. Badania prowadzono w kontrolowanych warunkach: stała temperatura otoczenia, wilgotność powietrza. Stwierdzono, iż czas schnięcia powłoki naniesionej na powierzchnie wypukłe (garby formy) jest dużo krótszy niż powłoki naniesionej na powierzchnie wklęsłe (wnęki). Różnice szybkości wysychania wynikają z odmienności warunków wymiany pary wydzielanej z powłoki do otoczenia.
Investigation results of the drying rate of the selected protective water coatings are presented in the paper. The water-based coating WC-R and alcohol-based coating Zirkofluid 1219 were subjected to examinations. They were drying kinetics of these coatings. The coating was applied to the cores of the mass matrix with a grain size of dL = 0.24 mm. In addition, the kinetics of the coating drying process was determined for three apparent viscosities: 11s; 20 s; 30 s. The coating viscosity was estimated by means of the Ford 4 mm cup. Drying rates of the protective coating were examined by using the gravimetric technique. Measurements were carried out in a continuous way under controlled conditions: constant ambient temperature and air humidity. It was found that the drying time of a coating applied to the convex surfaces (humps mould) is much shorter than the coating applied to the surfaces of the concave (cavities). Differences in the rate of drying due to differences in the exchange of a vapour of the coating secreted into the surroundings.
Źródło:
Archives of Foundry Engineering; 2014, 14, 2 spec.; 39-44
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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