Wyniki wyszukiwania - BazTech

1

Reflectivity of anodised Al-Si alloy surface of belt pulleys used in combustion engines

Labisz Krzysztof

Zeszyty Naukowe. Transport / Politechnika Śląska

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2021

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z. 112

125--133

EN

The recent trend of using aluminium alloys instead of steel has reached the transportation industry, where increasingly, more parts are made of aluminium. An example is the belt pulley, applied for combustion engines for energy transmission. This part should be strong, durable, and lightweight. Aluminium-silicon alloys are a good choice, moreover, even when the surface is anodised, also because of their moderate inertia control and excellent wear characteristic during mechanical operations. Since aluminium is lightweight yet mechanically durable and anodised, it is an ideal belt pulley to use, especially in high-temperature operations. However, the main question is what type of Al-Si alloy, casting method and anodisation method should be used in terms of energy adsorption, having long-term properties for a lifetime, has to be applied. For this reason, this paper presents the influence of the chemical composition, casting method and anodising parameters on the structure and thickness of the anodic layer produced on aluminium alloys, as well as on the albedo value as an ability to reflect or absorb light. The aluminium alloys, AlSi12Cu1 and AlSi9Cu3, were used as research materials, obtained using different casting methods. The goal of this work was to determine the optimal combination of the anodisation conditions and materials for maximising the reflectivity factor of the surface, as a very important factor, determining the energy amount absorbed by an anodised surface. For further improvement of these surface properties as well as for enhancement of the properties and strengthen the material produced with different aluminium alloys production methods, different alloying additives were added. In addition, the mechanical properties of the surface layer were measured, where a remarkable hardness increase was obtained, and the best combination in form of AlSi12Cu1 high pressure cast was found with the highest albedo factor among all tested surface variants.

2

Influence of Runner Geometry on the Gas Entrapment in Volume of Pressure Die Cast

Majernik J., Podařil M.

Archives of Foundry Engineering

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2019

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iss. 4

33--38

EN

The high pressure die casting technology allows the production of complex casts with good mechanical properties, with high production repeatability within narrow tolerance limits. However, the casts are somewhat porous, which may reduce their mechanical properties. There are several recommendations for reducing the porosity of casts, which are aimed at setting the technological parameters of the casting cycle. One of the primary and important ways to reduce the porosity and air entrapment in the melt is a suitable gating system design. Submitted contribution is devoted to assessing the influence of the runner branching geometry on the air entrapment within the cast volume during the filling phase of the casting cycle. Four variants of the gating system for a particular cast are compared with different design of main runner branching. The initial design is based on a real gating system where the secondary runner is connected to the main runner at an angle of 90 °. The modified designs are provided with a continuous transition of the main runner into the secondary ones, with the change in the branching runner radius r1 = 15 mm, r2 = 25 mm and r3 = 35 mm. The air entrapment in the melt is assessed within the cast volume behind the cores, which have been evaluated as a critical points with respect to further mechanical treatment. When designing the structural modification of geometry it was assumed that by branch changing using the radius value r3 = 35 mm, the melt flows fluently, and thus the value of the entrapped air in the volume of the cast will be the lowest. This assumption was disproved. The lowest values of entrapped air in the melt were found in the casts with runner transition designed with radius r1 = 15 mm. The conclusion of the contribution explains the causes of this phenomenon and from a designing point of view it presents proposal for measures to reduce the entrapment of the air in casts.

3

Mikrostruktura odlewów ze stopu AZ91 otrzymanych z zastosowaniem gorącokomorowych maszyn ciśnieniowych

Braszczyńska-Malik K. N., Cibis R., Braszczyński J.

Archiwum Odlewnictwa

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2004

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R. 4, nr 11/1

72--77

PL

Przedstawiono charakterystykę mikrostrukturalną odlewów ze stopu magnezu AZ91 wykonanych z zastosowaniem gorącokomorowej maszyny ciśnieniowej. Struktura odlewów była efektywnie rozdrobniona (około 10-krotnie) w porównaniu z odlewami piaskowymi. Obserwowano roztwór stały &alpha oraz międzymetaliczną fazę &gamma (Al12Mg17).

EN

Microstructural characterization of high pressure die cast magnesium alloy AZ91 was presented. The alloy have been poured in a 250 t hot chamber high pressure die cast machine. The microstructure of casting was effective refinement (about 10 times) compared with sand casting. The &alpha-Mg and intermetallic &gamma-phase were observed.