Features of Glass Plate Hardening by the Ion Exchange Method

In this work various methods of glass plate hardening are considered. These plates are used to protect defense devices. As a glass was used system R2O-B2O3-SiO2. The method of thermal hardening was considered. Technological disadvantages of this method were discovered by analyzing Newton's rings and a polarizing plate. The use of chemical hardening has shown its advantages over the thermal method. The essence of the method is the ion exchange of alkali metals between glass plates and the chemical mixture melt. The operating principle of the chemical hardening equipment and its technology were considered. As a result, hardened glass plates with preservation of planar geometry were obtained.

Kinetic Viscoelasticity of Crosslinking Epoxy Asphalt

Epoxy modification of asphalt binders has been recognized as a very effective technology to alter the chemistry of asphaltic materials in such a way that long-lasting pavement structures can be designed. However, the phenomena that are involved to build up the physico-mechanical properties of epoxy asphalt systems are still unknown. The focus of this paper is on understanding the link between chemistry and the mechanical properties of epoxy asphalt binders during the thermo-irreversible process of chemical hardening. For this purpose, a constitutive model for predicting the evolution of cure-induced stresses in epoxy asphalt binders is proposed, and an experimental program was developed to determine the model parameters. The cure dependency of physico-mechanical parameters of modified binder was obtained and imported into the model to simulate the build-up of material properties during (non-)isothermal hardening of epoxy asphalt binder. The model is implemented in a commercially finite element tool by coupling the chemical, thermal, and mechanical phenomena with multi-physics strategies, and the results are analyzed to identify the influence of different heating conditions on the crosslinking density and subsequently on stress build-up. It was found that the amount of stress build-up during curing was strongly dependent on the heating conditions, and a higher rate of stress build-up was observed at higher applied temperatures. In other words, the processing conditions during in-plant material production or in-field manufacturing of structures made by epoxy asphalt systems affect the material hardening and subsequently the desired functionalities of pavement structures.

Effective Laboratory Method of Chromite Content Estimation in Reclaimed Sands

The paper presents an original method of measuring the actual chromite content in the circulating moulding sand of foundry. This type of material is applied for production of moulds. This is the case of foundry which most frequently perform heavy casting in which for the construction of chemical hardening mould is used, both the quartz sand and chromite sand. After the dry reclamation of used moulding sand, both types of sands are mixed in various ratios resulting that in reclaimed sand silos, the layers of varying content of chromite in mixture are observed. For chromite recuperation from the circulating moulding sand there are applied the appropriate installations equipped with separate elements generating locally strong magnetic field. The knowledge of the current ratio of chromite and quartz sand allows to optimize the settings of installation and control of the separation efficiency. The arduous and time-consuming method of determining the content of chromite using bromoform liquid requires operational powers and precautions during using this toxic liquid. It was developed and tested the new, uncomplicated gravimetric laboratory method using powerful permanent magnets (neodymium). The method is used in the production conditions of casting for current inspection of chromite quantity in used sand in reclamation plant.