In this article the structural and mechanical properties of grain refinement of Cu-Sn alloys with tin content of 10%, 15% and 20% using the KOBO method have been presented. The direct extrusion by KOBO (name from the combination of the first two letters of the names of its inventors – A. Korbel and W. Bochniak) method employs, during the course of the whole process, a phenomenon of permanent change of strain travel, realized by a periodical, two-sided, plastic metal torsion. Moreover the aim of this work was to study corrosion resistance. The microstructure investigations were performed using an optical microscope Olimpus GX71, a scanning electron microscope (SEM) and a scanning transmission electron microscope (STEM). The mechanical properties were determined with INSTRON 4505/5500 machine. Corrosion tests were performed using «Autolab» set – potentiostat/galvanostat from EcoChemie B.V. with GPES software ver. 4.9. The obtained results showed possibility of KOBO deformation of Cu-Sn casting alloys. KOBO processing contributed to the refinement of grains and improved mechanical properties of the alloys. The addition of tin significantly improved the hardness. Meanwhile, with the increase of tin content the tensile strength and yield strength of alloys decrease gradually. Ductility is controlled by eutectoid composition and especially δ phase, because they initiate nucleation of void at the particle/matrix interface. No significant differences in the corrosion resistance between cast and KOBO processed materials were found.
High-tin bronzes are used for church bells and concert bells (carillons). Therefore, beside their decorative value, they should also offer
other functional properties, including their permanence and good quality of sound. The latter is highly influenced by the structure of bell
material, i.e. mostly by the presence of internal porosity which interferes with vibration of the bell waist and rim, and therefore should be
eliminated. The presented investigations concerning the influence of tin content ranging from 20 to 24 wt% on mechanical properties of
high-tin bronzes allowed to prove the increase in hardness of these alloys with simultaneous decrease in the tensile and the impact
strengths (Rm and KV, respectively) for the increased tin content. Fractures of examined specimens, their porosity and microstructures
were also assessed to explain the observed regularities. A reason of the change in the values of mechanical properties was revealed to be
the change in the shape of α-phase crystals from dendritic to acicular one, and generation of grain structure related to the increased Sn
content in the alloy.
Results of scientific researches show the trend of active using nitrides and borides of transition
metals and their combination in developing protective materials. While single elements
nitrides have been well studied, their multilayer modifications and combinations require
more detailed study. Physical-mechanical properties and structural-phase state of multilayer
coating according to the deposition conditions is an important task for the study.
It will be the analysis of physical-mechanical and electrical properties of coatings based on
refractory metals nitrides, their structure and phase composition and surface morphology
depending on the parameters of condensation. It was established the structure and behavior
of nano scale coatings based on refractory metals nitrides (Ti, Zr) depending on the size
of nano grains, texture, stress occurring in coatings.
The aim of this work was to produce a thin SnO2 film by a technique combining the sol-gel method and electrospinning from a solution based on polyvinylpyrrolidone and a tin chloride pentahydrate as a precursor. The spinning solution was subjected to an electrospinning process, and then the obtained nanofiber mats were calcined for 10 h at 500°C. Then, the scanning electron microscopy morphology analysis and chemical composition analysis by X-ray microanalysis of the manufactured thin film was performed. It was shown that an amorphous-crystalline layer formed by the SnO2 nanofiber network was obtained. Based on the UV-Vis spectrum, the width of the energy gap of the obtained layer was determined.
The most important feature of bells is their sound. Their clarity and beauty depend, first of all, on the bell’s geometry - particularly the shape of its profile and the mechanical properties of alloy. Bells are the castings that work by emitting sound in as-cast state. Therefore all features that are created during melting, pouring, solidification and cooling processes will influence the bell's sound. The mechanical properties of bronze depend on the quality of alloy and microstructure which is created during solidification and depend on its kinetics. Hence, if the solidification parameters influence the alloy’s properties, how could they influence the frequencies of bell`s tone? Taking into account alterable thickness of bell's wall and differences in microstructure, the alloy's properties in bell could be important. In the article authors present the investigations conducted to determine the influence of cooling kinetics on microstructure of bronze with 20 weight % tin contents.
The exudation layer seriously affects the properties and the surface finish of the tin bronze alloy. The effective control of the exudation thickness is important measure for improving the properties of the alloy. In order to study the influence of process parameters on the thickness of exudate layer, the tin bronze alloy was prepared by continuous unidirectional solidification technology at different process parameters. The microstructure of the continuous unidirectional solidification tin bronze alloy was analyzed. The effect of process parameters on microstructure and chemical compositions was studied by orthogonal experiment. The results show that there exists an exudation layer on the surface of the continuous unidirectional solidification tin bronze alloy, and the exudation is mainly composed of a tin-rich precipitated phase. It indicates that the continuous casting speed is the main factor affecting the thickness of exudation layer, followed by mold temperature, melt temperature, cooling water temperature and cooling distance.
The most important feature of bells is their sound. Its clarity and beauty depend, first of all, on the bell’s geometry - particularly the shape
of its profile, but also on the quality of alloy used to its cast. Hence, if the melting and pouring parameters could influence the alloy’s
properties, what influence they would have on the frequencies of bell’s tone. In the article authors present their own approaches to find
answers on that and more questions.
The mold temperature of the downward continuous unidirectional solidification (CUS) cannot be controlled higher than the liquidus of alloys to be cast. Therefore, the continuous casting speed becomes the main parameter for controlling the growth of columnar crystal structure of the alloy. In this paper, the tin bronze alloy was prepared by the downward CUS process. The microstructure evolution of the CUS tin bronze alloy at different continuous casting speeds was analysed. In order to further explain the columnar crystal evolution, a relation between the growth rate of columnar crystal and the continuous casting speed during the CUS process was built. The results show that the CUS tin bronze alloy mainly consists of columnar crystals and equiaxed crystals when the casting speed is low. As the continuous casting speed increases, the equiaxed crystals begin to disappear. The diameter of the columnar crystal increases with the continuous casting speed increasing and the number of columnar crystal decreases. The growth rate of columnar crystal increases with increasing of the continuous casting speed during CUS tin bronze alloy process.
The paper presents the effect of tin on the crystallization process, microstructure and hardness of cast iron with compacted (vermicular) graphite. The compacted graphite was obtained with the use of magnesium treatment process (Inmold technology). The lack of significant effect of tin on the temperature of the eutectic transformation has been demonstrated. On the other hand, a significant decrease in the eutectoid transformation temperature with increasing tin concentration has been shown. It was demonstrated that tin narrows the temperature range of the austenite transformation. The effect of tin on the microstructure of cast iron with compacted graphite considering casting wall thickness has been investigated and described. The carbide-forming effect of tin in thin-walled (3 mm) castings has been demonstrated. The nomograms describing the microstructure of compacted graphite iron versus tin concentration have been developed. The effect of tin on the hardness of cast iron was given.
Tin dioxide (SnO2) is an n-type semiconductor and has useful characteristics of high transmittance, excellent electrical properties, and chemical stability. Accordingly, it is widely used in a variety of fields, such as a gas sensor, photocatalyst, optoelectronics, and solar cell. In this study, SnO2 films are deposited by thermal atomic layer deposition (ALD) at 180°C using Tetrakis(dimethylamino)tin and water. A couple of 5.9, 7.4 and 10.1nm-thick SnO2 films are grown on SiO2/Si substrate and then each film is annealed at 400°C in oxygen atmosphere. Current transport of SnO2 films are analyzed by measuring current – voltage characteristics from room temperature to 150°C. It is concluded that electrical property of SnO2 film is concurrently affected by its semiconducting nature and oxidative adsorption on the surface.
The possibility of Cu(II), Ni(II) and Sn(II) removal from model solutions and real wastewater from
the production of PCBs using Na2
CS3
for precipitation was presented in this paper. The testing was carried out
on a laboratory scale using model and real industrial wastewater containing additives in the form of complexing
compounds used in the production of PCBs (Na2
EDTA, NH3(aq), thiourea) and recommended by the USEPA
(Na3
MGDA, Na4
GLDA). Application of Na2
CS3
in optimal conditions of conducting precipitation process was
connected with obtaining wastewater containing low concentrations of metals (Cu 0.02 mg/L, Sn <0.01 mg/L, Ni
<0.005 mg/L at pH 9.39 and Cu 0.07 mg/L, Sn <0.01 mg/L, Ni 0.006 mg/L at pH 7.79). Controlled application of
Na2
CS3
by the use of a platinum redox electrode was also connected with obtaining treated wastewater containing
low concentrations of metals (Cu 0.019 mg/L, Sn <0.05 mg/L, Ni <0.0098 mg/L at pH 9–9.5 and E= -142 mV in the
laboratory scale and Cu 0.058 mg/L, Sn <0.005 mg/L, Ni 0.011 mg/L at pH 9.14 and E= +10 mV in the industrial
scale). Changing the value of redox potential of treated wastewater by dosing Na2
CS3
made it possible to control
the precipitation process on laboratory and industrial scale by the use of a platinum redox electrode. Controlled
application of Na2
CS3
can be used to remove Cu(II), Ni(II) and Sn(II) from industrial effl uent containing chelating
compounds like Na2
EDTA, NH3(aq), thiourea, Na3
MGDA and Na4
GLDA.