Jae-Min Cha

Effects of Substituting B 2 O 3 for P 2 O 5 on the Structure and Properties of SnO-P 2 O 5 Glass Systems

The investigation is directed to lead free (Pb-free) frits that can be used for organic light emitting diode, plasma display screen devices and other sealing materials. -SnO system glasses have been prepared for Pb-free low temperature glass frit. Structure and properties of the glasses with the composition SnO- (x

Analysis of viscoelastic flow in tin phosphate glass

The change of the viscoelastic flow near the imprinting temperature was analyzed by a penetration method with a commercial TMA and the result was compared with thermally-imprinted SnO-P2O5 (SP) and SnO-B2O3-P2O5 (SBP) glass samples by an imprint apparatus. The viscosity of SP glass increases monotonically with increasing SnO content and the specific movement is shown in viscoelastic flow under the optimized thermal imprinting temperature for SP glasses.

Mechanical Property and Crystallization of Glass by Femtosecond Laser Pulses

Generally, the strength achieved of glass-ceramics is higher as is the fracture toughness, as compared with the original glass. This improvement is due to the microstructure consisting of very small crystals. In this study, Ag-doped 45SiO₂-24CaO-24Na₂O-4P₂O 5 glasses were irradiated to strengthen by the crystallization using Femto second laser pulses. Through the UV/VIS spectroscope, XRD, Nano-indenter and SEM etc., heat-treated and irradiation of laser pulses without heat-treated samples were analyzed. Two kinds of samples, heat-treated and laser irradiated without heat-treated samples, showed the peaks in the same wavelength near 360 nm. Especially, samples irradiated by 140 mW laser with XYZ stage having at the rate of 100~1000 μm/s had the largest absorption peak among them, and heat-treated samples was shown lower absorption range than over 90 mW laser irradiated samples. Moreover, samples irradiated by laser had higher values (4.4~4.56×10 -3 (Pa)) of elastic modulus which related with strength of glass than values of heat-treated samples and these are 1.2~1.5 times higher values than them of mother glass.

Study on the Water Durability of Molybdate Glasses with B 2 O 3 as Low Temperature Sealing Materials

The boron alkali molybdate glass system was investigated as lead-free low-temperature melting sealing materials, with different boron oxide contents between 0 and 8 mol%. The glasses were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), infrared spectroscopy (IR), and by densities. Their chemical properties were measured by their dissolution rates (DR) and by Product Consistency Test (PCT). As the boron oxide contents were increased, the glasses maintained their low temperature properties (Tg under 175 °C) and new network formers of [BO3] triangular units and [BO4] tetrahedral units appeared. The results confirmed that boron oxide doped molybdate glass is a candidate low-temperature sealing material. The introduction of small amounts of B2O3 causes a change in the amorphous network’s main structural units from molybdate units to a mixture of molybdate and borate units. The glasses possess MoO4, MoO6, BO3 and BO4 groups as basic structural units. In this study, the amount of MoO3 was much higher than that of B2O3, so the boroxol ring structure occurred much less frequently than molybdates as a network former. But addition of B2O3 leads to an increase in the number of bridging oxygens and strengthens the glass network. As a result, the overall glass system becomes more rigid, and chemical durability is improved. †(Received May 8, 2017; Accepted July 31, 2017)