The paper presents results of measuring heat diffusivity and thermal conductivity coefficients of used green foundry sand in temperature
range ambient – 600 o
C. During the experiments a technical purity Cu plate was cast into the green-sand moulds. Basing on measurements
of the mould temperature field during the solidification of the casting, the temperature relationships of the measured properties were
evaluated. It was confirmed that the obtained relationships are complex and that water vaporization strongly influences thermal
conductivity of the moulding sand in the first period of the mould heating by the poured and solidified casting
The paper presents results of measuring attenuation coefficient of the Al-20 wt.% Zn alloy (AlZn20) inoculated with different grain
refiners. During experiments the melted alloys were doped with Al-Ti3-C0.15 refining master alloy. Basing on measurements performed
by Krautkramer USLT2000 device with 1MHz ultrasound wave frequency it was stated that grain refinement reduces the attenuation
coefficient by about 20-25%. However, the examined alloys can be still classified as the high-damping ones of attenuation greater than 150
dB/m.
The paper is devoted to grain-refinement of the medium-aluminium zinc based alloys (MAl-Zn). The system examined was sand cast Zn10
wt. %. Al binary alloy (Zn-10Al) doped with commercial Al-3 wt. % Ti – 0.15 wt. % C grain refiner (Al-3Ti-0.15C GR). Basing on the
measured attenuation coefficient of ultrasonic wave it was stated that together with significantly increased structure fineness damping
decreases only by about 10 – 20%. The following examinations should establish the influence of the mentioned grain-refinement on
strength and ductility of MAl-Zn cast alloys.
The subject of the paper is structural stability of the Zn-26 wt.% Al binary alloys doped with 2.2 wt.% Cu or 1.6 wt.% Ti addition. The structural stability of Zn-Al alloys with increased Al content is connected with stability of solid solution of zinc in aluminium α', which is the main component of these alloys microstructure. Such a solution undergoes phase transformations which are accompanied, among others, by changes in dimensions and strength properties. The structural stability of the ZnAL26Cu2.2 and ZnAl26Ti1.6 alloys was investigated using XRD examinations during long term natural ageing after casting, as well as during long term natural ageing after super-saturation and quenching. On the basis of the performed examinations it was stated that small Ti addition to the binary ZnAl25 alloy, apart from structure refinement, accelerates decomposition of the primary α' phase giving stable structure in a shorter period of time in comparison with the alloy without Ti addition. Addition of Ti in amount of 1.6 wt.%, totally replacing Cu, allows obtaining stable structure and dimensions and allows avoiding structural instability caused by the metastable ε−CuZn4 phase present in the ZnAl26Cu2.2 alloy.
The paper presents results of measuring thermal conductivity and heat capacity of bentonite foundry sand in temperature range ambient –
900 OC. During the experiments a technical purity Cu plate was cast into the green-sand moulds. Basing on measurements of the mould
temperature field during the solidification of the casting, the temperature relationships of the measured properties were evaluated. It was
confirmed that water vaporization strongly influences thermal conductivity of the moulding sand in the first period of the mould heating by
the poured casting.