Papers by Keyword: Dry Ice

Abstract: This paper presents the results of static compression tests of concentrated crystallized carbon dioxide. The test results obtained under this research describe the relationship between the compressive stress and strain allowing to estimate the proportionality ratio, limit stress and critical stress values. Special test methods were used due to low temperature of crystallized carbon dioxide (minus 78.5°C) and its sublimation under standard testing conditions. The results of the mechanical properties of agglomerated CO₂ were compared with the mechanical properties of other known materials. This allowed us to derive assumptions, which can become the starting point of the process to build a mathematical model describing the dry ice compaction and granulation processes.

Abstract: Graphene was fabricated by a well-known technique of ignition of magnesium (Mg) metal ribbon in solid carbon dioxide. Two dry ice slabs were used as carbon source for the production of graphene. A hemispherical cavity of about 3-4 cm diameter was carved on surfaces of both dry ice slabs. About 0.5g of Mg ribbon was burnt and immediately placed into the dry ice cavity. It was then covered up by another carved slab of dry ice. After complete combustion, mixture of black and white residues was formed. It was then recovered. 20 ml of 1 M HCl acid was added to the product mixture. Reaction of HCl with MgO and unburned Mg formed MgCl₂ which was then washed away by deionized water. The isolated carbon material was separated as product. Characterization of the product was performed using optical microscopy (OM), where images showed the presence of sheet-like light gray objects. Field emission scanning electron microscopy (FESEM) and transmission electron microscope (TEM) analyses revealed the presences of graphene. The lateral length of the sheet was about 3-3.5 μm and the surface area was about 3-5.5 μm² using images analysis software.

Abstract: This work concerns the changes to wood surface morphology induced by surface cleaning with dry ice. The surface roughness values demonstrated that the surface treatment with dry ice resulted in amplified surface roughness, mainly due to the increase in the roughness of early wood. The treatment of old wood with dry ice not only guarantees effective removal of contamination from the wood surface, it also induces positive changes in other (such as wettability, surface free energy, color, and similar). This way of wood surface treatment guarantees more wood surface quality for the surface treatment, impregnation or gluing.

Abstract: In this paper, dry ice is converted into few-layer graphene, which can be dispersed stably in N, N-Dimethylformamide (DMF) by adding pyrene-1-boronic as a stabilizer that non-covalently functionalizes the surface of graphene to obtain homogeneous colloidal suspensions. Moreover, we make use of vacuum filtration transferring for fabricating transparent conducting graphene films by incorporating multiwalled carbon nanotubes (MWNTs). The increased conductivity is ascribed to the formation of a more efficient network. Here a transmittance of 81% at 550 nm and a sheet resistance as low as 38.17 KΩ/sq are obtained.

Abstract: The characteristics of dry ice particles produced by expanding liquid carbon dioxide and its application for surface cleaning have been studied experimentally. The production of the dry ice particles was based on the Joule-Thomson effect. The ejected dry ice particles were observed using a high-speed microscope camera. Through digital image processing, the particle size and particle velocity in the jet were analyzed. To in-situ measure the size distribution of the dry ice particles, a laser diffraction method was used. The experimental results showed that the primary dry ice particles ejected from the expansion nozzle were about 1 μm in mass median diameter. The presence of a thermally insulated tube at the outlet of the nozzle enhanced the agglomeration of the particles, whereby agglomerates of about 100 μm in mass median diameter were formed. The performance of dry ice jet for removing fine particles adhering to surfaces was also evaluated using microscopic observation. It was found that the particle removal process consists of two stagesslow removal stage and rapid removal stagethat are related to the jet temperature.