Numerical Investigation of Iron Ore Tailings Filled Epoxy Composite as Heat Resistant Material

The thermal properties of epoxy composites reinforced with iron ore tailings were used to investigate the thermal performance of the composite as heat resistant material. Thermal properties are important parameters for determining the behaviour and appropriate applications of materials. This paper focuses on investigating the thermal performance of epoxy composite reinforced with iron ore tailings (IOT) of particles sizes 150 µm, 10% reinforced. The thermal properties of the selected epoxy-IOT composite were specific heat capacity – 2352 J/kg-K, thermal resistivity – 4.788 °C-m/W, thermal diffusivity – 0.089 mm2/s and Thermal conductivity – 0.209 W/m-K. The selected epoxy-IOT composite was numerically compared with an existing material (gypsum board) of the following thermal properties: specific heat capacity – 1090 J/kg-K, thermal resistivity – 3.87°C-m/W, thermal diffusivity – 0.333 mm2/s and Thermal conductivity – 0.258 W/m-K. The numerical analysis was done using Autodesk Fusion360, by modelling the materials as slabs.The heat transfer process of the composite and the prediction of the heat resistance capability were explained by comparing the results with an existing material (gypsum plasterboard) using their mechanical and thermal properties.The numerical results indicated that the epoxy-IOT composite has lower minimum temperature and thermal stress compared with the existing material (gypsum board), which implies that epoxy-IOT composite when used as a heat insulator will resist heat and sustain thermal stress better than the gypsum board of the same geometry under the same conditions. In conclusion, an epoxy-IOT composite of appropriate mixing ratio and geometry can be comfortable use as heat resistant materials. Keywords— Epoxy-IOT, Numerical Analysis, Temperature Distribution, Thermal Performance, Thermal Stress

The Formation of Nanoscale Closed Graphene Surfaces during Fullerite C60 Hot Isostatic Pressing

The fullerite C60 modified by hot isostatic pressing (HIP) at 0.1 GPa in argon near and beyond its thermal stability region (920–1270 K temperature interval) was studied by X-ray diffractometry, Raman spectroscopy, ultra soft X-ray photoelectron and near edge X-ray absorption fine structure spectroscopy. It was found that the C60 molecules merge into closed nanocapsules with a graphene surface during the thermal treatment. The conducted studies showed that using HIP treatment of the fullerite C60, it is possible to obtain a chemically resistant material with a high hardness and elasticity, as well as a density lower than that of the graphite. This new material, consisting of closed graphene nanocapsules 2–5 nm in size, formed by sp2 covalent bonds between carbon atoms is promising for various applications, and as a basis for the synthesis of new composite materials.

Study of the properties of chemically resistant repair mortar with the use of secondary raw materials

This paper deals with the research of a new silicate-based repair mortar modified with selected secondary raw materials. The aim of this work is to develop a chemically resistant material suitable for use in an extremely aggressive environment of sewers. The monitored parameters include key physical-mechanical characteristics, resistance to sulphate ions and to the attack of aggressive biogenic sulfuric acid. Chemical resistance was tested by simulating the exposure environment in laboratory conditions, according to the methodology of DIN 19573. The obtained results show that by suitable modification of the reference mortar it is possible to maintain the values of physical-mechanical characteristics and improve the chemical resistance of test samples.

BIOPLASTIC MADE OF ORANGE PEELS

This study uses orange peel waste to create a biopolymer that can be used for different purposes. In order to achieve this, we evaluated various technologies for the production of the biopolymer, and tried to design the most environmentally friendly process possible. One of the reasons why this bioplastic should be manufactured is to participate in the replacement of common environmental hazardous plastic, which has been banned in many places. On the other hand, using orange peel as the main ingredient is an alternative and gives value to an organic waste that has limited use in circular economy solutions. In this research we present a methodology to create a bioplastic of orange peels. As a result, we obtained a biodegradable, flexible and resistant material to be used in the manufacture of containers, utensils, etc. In addition, it is a material that, given the raw materials used, is considered GRAS (Generally Recognized As Save), implying a non-toxic product that is safe for the consumer.

Process for coating surfaces with a copolymer made from sulfur and dicyclopentadiene

The reaction between sulfur and dicyclopentadiene was optimised to form a shelf stable and soluble low molecular weight oligomer. After a simple curing process at 140 °C the material was rendered insoluble and resistant to acids and solvents. Taking advantage of the soluble oligomer, a metal surface was coated with the dissolved material which was then cured to show that a copolymer layer can act as a corrosion resistant material. Further, silica gel was coated with the soluble oligomer to test mercury removal applications. Even after curing, the polymer coated silica was an effective mercury sorbent. Additionally, the sorbent was also used to remove mercury form a diesel and water mixture indicating that mercury removal from a mixture of organic and aqueous substances is possible with this system.

The New Chemically Resistant Material for the Invert Grouting Optimized by Secondary Raw Material

This paper deals with the development of a new mortar, for cement-based inverse grouting, with an increased degree of chemical resistance. The aim of this work is to verify new mixtures optimized by suitable secondary raw materials. The studied parameters include selected physical-mechanical characteristics and chemical resistance of individual raw material variants is characterized by resistance to sulfate solution. The results of this work show that it is possible to increase the chemical resistance by optimizing the grouting mortar mixture with suitable secondary raw materials. The optimized mixture for the new grout will be part of a comprehensive material system for the remediation of sewers or shafts.

Zircônia na odontologia: mini-revisão

Purpose: This study aims to provide knowledge to clinicians about general aspects of zirconia and to approach the introduction of different zirconia generations. Methods: An electronic search of the English current literature was conducted including scientific articles published up to 2019. Results: According to the selected articles, important differences were found in terms of the novel compositions of zirconia, microstructures among the materials, differences in cubic phase content and yttria in the tetragonal phase, leading to different optical, mechanical and aging resistance properties. Conclusion: Zirconia is the most resistant material available among ceramics with mechanical and optical differences on available materials. The introduction of the monolithic crowns solving the veneering delamination but structural modifications were necessary to provide adequate translucency.