Low Melting Point Glass Research Articles

Laser Assisted Frit Sealing for High Thermal Expansion Glasses

Analysis of laser assisted frit sealing processes for high CTE > 5x10 -6 /°C (coefficient of thermal expansion) glasses was done. The method is based on the thermal fusion of two glasses with a low melting point glass frit. This method is used when thermal sensitive materials such as OLED (organic light emissive device) are present in the glass package. The frit is selected to be highly absorbent at the sealing laser wavelength, while the glasses are transparent at the sealing wavelength. It was found that laser sealing of a high CTE glass with sealing conditions optimized for a low CTE (< 5x10 -6 /°C) glass, such as glass suitable for display devices, produces very poor results. The issue with sealing glasses with high CTE is high transient stress formed during heating and cooling the glass to the sealing temperatures. The sealing yield of high CTE glasses could be significantly improved by increasing “residential heating time” by reducing sealing speed or increasing laser spot size. This results in lower cooling rate of the glass and helps to reduce the residual stress. This was confirmed by stress analysis showing a reduction of the stress for soda lime glass with increasing residential heating time.

A novel heat-resistant organic matrix adhesive for hydrophobic silica aerogels composites and 1Cr18Ni9Ti steel bonding

The novel organic matrix adhesive was used to join hydrophobic mullite fiber reinforced silica aerogels (HMF/SA) composites and 1Cr18Ni9Ti steel. It was prepared using silicone resin (SR) as a matrix, Al, low melting point glass (GP), ZnO and Fe2O3 powders as inorganic fillers, γ-aminopropyltriethoxysilane (γ-APS) as curing agent and dibutyltin dilaurate (DBTDL) as catalyst. The curing mechanism and character of the adhesive were studied, as well as the bonding mechanism of the adhesive. The tensile shear strength of the adhesive was investigated after heat-resistant experiment in atmosphere surroundings. Results showed that the adhesive could be cured at room temperature through polycondensation reaction using γ-APS. The adhesive had a good wettability with HMF/SA composites and 1Cr18Ni9Ti steel, and established strong adhesion between both of them. The adhesive could be resistant to 750°C with satisfactory bonding strength (4.68MPa). The optimized ratio of inorganic fillers had important influences on the bonding properties of the adhesive. Al took an important effect in giving a strong refractory ceramic bond to the adherends. Failure mode of joint was substrate failure due to the high chemical bonding force between the adherends.

Preparation of high-temperature organic adhesives and their performance for joining SiC ceramic

Two kinds of high-temperature organic adhesives were prepared and successfully applied to join SiC ceramic. One adhesive was composed of preceramic polymer (V-PMS) and B4C powder (HTA-1), and the other was composed of V-PMS, B4C powder and low melting point glass powder (HTA-2). The properties of the obtained adhesives were investigated by TGA, XRD, bonding test and SEM analysis. The results show that the obtained adhesives exhibit outstanding heat-resistant property and excellent bonding strength. The bonding strength of HTA-1 treated at 200°C, 400°C, 600°C were 26.8MPa, 18.9MPa, 7.3MPa, respectively. When the temperature increased to 800°C or even higher, the shear strengths of the joints were enhanced to over 50MPa. Moreover, by adding glass powder as the second filler, it was found that the minimum shear strength of HTA-2 was enhanced to 16.4MPa. The excellent performances of the obtained adhesives make them as promising candidates for joining SiC ceramics for high-temperature applications.

Effect of Refinement Process Condition and Sintering Property on the Low Melting Point Glass Powder by High-pressure Homogenization Technology

Using carboxymethyl cellulose(CMC) as an anti-settling agent of low melting point glass powder aqueous dispersion,the high-pressure homogenizer can refine glass powder particle to reduce their size.Different high-pressure homogenized time affected on glass powder’s particle size and the sintering property.Under the same pressure(50 MPa) a longer high-homogeneous time gets smaller particle size and narrows particle size distribution.And the softening temperature and sintering temperature are also lower.The results show that the high-pressure homogenizer techniques can be used to reduce the particle size of the glass powder,so that the softening temperature and sintering temperature will be lowered.

Highly efficient and stable dye-sensitized solar cells from adding low melting point glass frits

TiO2 films were modified by adding a low melting point glass frit as a light scattering particle and applied to an anode electrode in dye-sensitized solar cells (DSSCs) to enhance the interconnection between TiO2 and fluorine doped transparent oxide. The optical properties, photovoltaic properties and microstructures of the photo electrodes were examined to determine the role of the low glass transition temperature (Tg) glass frit. Electrochemical impedance spectroscopy, the Brunauer-Emmett-Teller method and a scratch test were conducted to support the results. The DSSC with the TiO2 film containing 3 wt% low Tg frit showed optimal performance (5.1%, efficiency) compared to the TiO2-based one. The photocurrent density slightly decreased by adding 3 wt% low Tg frit due to its large size and non-conductivity. However, the decrease of current density was compensated for by the scattering effect, high surface area and low electron transfer impedance at the electrolyte-dye-TiO2 interface.

Preparation and characterization of carbonyl iron/glass composite absorber as matched load for isolator

Composite absorbers made from 66wt% carbonyl iron and 34wt% low melting point glass powder were prepared by a pressureless sintering technique in a nitrogen atmosphere. Apparent porosity and bending strength of the as-prepared composites were investigated. The microstructure, heat resisting properties and electromagnetic properties were characterized by scanning electron microscopy, thermal gravimetric analysis–differential scanning calorimetry and vector network analyzer. The results show that the carbonyl iron/glass composite absorbers were difficult to densify. As the sintering temperature and soaking time increased, the apparent porosity first decreased and then increased, whereas the bending strength showed the opposite change. The composite absorber sintered at 520°C for 40min achieved the minimum apparent porosity of 13.08% and the highest bending strength of 52MPa. Compared to the carbonyl iron/silicone rubber absorber, the carbonyl iron/glass composite absorber exhibited better heat resisting properties, and the initial oxidation temperature was increased about 200°C. The composite absorber with a thickness of 1.25mm showed a good microwave absorbing property in 8–12GHz.

The preparation and performance of a novel room-temperature-cured heat-resistant adhesive for ceramic bonding

A novel adhesive for joining ceramic materials was made using silicon–epoxy interpenetrating polymer networks (IPNs) as matrix (based on silicon resin (SR) and diglycidyl ether of bisphenol A (DGEBA) epoxy resin (EP)), γ-glycidoxypropyltrimethoxysilane (γ-GPS) as cross-linking agent, dibutyltin dilaurate (DBTDL) as catalyst, Al, low melting point glass (GP) and B4C powders as inorganic fillers, low molecular polyamide (LMPA 650) as curing agent. The character and heat-resistance property of the IPNs and adhesive were tested by FT-IR, DSC and TG. The compressive shear strength of ceramic joints was investigated at different temperatures in atmosphere surroundings. The modification mechanism of inorganic fillers was studied using XRD. Results showed that the IPNs were a homogeneous morphology of inter-crosslinked network structure with single Tg. The adhesive could be cured at room temperature with good heat-resistance property due to the chemical bond of epoxy group and Si–O–Si. The optimum compressive shear strength (9.44MPa at 1000°C) occurred at SR/EP ratio: 9/1, content of KH560: 2%, Al/GP/B4C ratio: 3.2/4/3, fillers/IPNs ratio: 6/4. The adhesive had good heat-resistance property with 10% weight loss at 435°C. Failure mode of joint was mixing failure due to the high chemical bonding force.

MgO-Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;-SiO&lt;sub&gt;2&lt;/sub&gt; Glass-Ceramic Prepared by Sol-Gel Method

The crystallization behavior of MgO-Al2O3-SiO2 glass-ceramics by sol-gel technology was investigated by using x-ray diffraction (XRD), differential thermal analysis (DTA), Scanning electron microscopy (SEM). The results showed that: (1)α-cordierite phase was precipitated when the green body was calcined at 1050°C, and α-cordierite of high purity and stability could be formed at 1100°C; (2) Adding an appropriate amount of low melting point glass powder into the green body may provide liquid-phase environment during the sintering process, which will help enhance the tightness density of glass-ceramic, and thus improve its flexural strength.

Effect of auxiliary on hysteresis property of ferroelectric film by aerosol deposition

Concerning the ferroelectric films produced by AD method, the effects by adding auxiliary agents to injection powder and the effects by grain size were investigated for the purpose of realizing higher ferroelectric property. Ferroelectricity of AD film was found to be improved by adding low melting point auxiliary agents and using calcined powder, and was also found to depend on the grain size of injection powder, and to be improved by increasing the size to an appropriate value. By optimizing the conditions, good ferroelectricity was realized; such as Pr = 25.4 micro C/cm2 in the heat treatment at 600°C (63% of sintered film, calcined powder added with low melting point glass) and Pr = 38.0 micro C/cm2 in the heat treatment at 700°C (95% of sintered film, calcined powder added with Bi2O3-ZnO).

PZT thick films for sensor and actuator applications

PZT thick films with thicknesses between 5 and 150 μm are of great interest for microsystems applications where direct coating onto microelectronic substrates and high electromechanical performance are required. Dense PZT thick films have been obtained by combining a PZT-PMN powder with a low melting point glass and the eutectic forming oxides Bi 2O 3 and ZnO. Densification is due to transient liquid phase formation with additional incorporation of cations into the growing PZT grains during sintering. PZT thick films prepared by this method show excellent dielectric, ferroelectric and piezoelectric properties. They have been applied on various substrates, like Al 2O 3, ZrO 2, Low Temperature Cofired Ceramics (LTCC) and silicon wafers which are basis materials for microsystems technology. The influence of the substrate material on the PZT thick film properties and the role of buffer layers will be discussed.

Wire drawing at elevated temperatures using different die materials and lubricants

By increasing the working temperature in a metal-forming operation, the flow stress of the material can be reduced considerably. This paper describes an experimental programme of wire drawing using different lubricants and dies at temperatures varying from ambient to 800°C. Dies made from tungsten carbide, HSS and maraging steel were used. An attempt at making Silicon Nitride dies was unsuccessful. Soap, colloidal graphite, polyethylene and low melting point glass were tested as lubricants, some of these being shown to be satisfactory under certain specific conditions. It was established that wire may be drawn at elevated temperatures, but with some die material, lubricant and tribology problems.

Low-temperature silicon-to-silicon anodic bonding with intermediate low melting point glan

Abstract Room-temperature silicon-to-silicon bonding has been performed. It is an electrostatic bonding using sputtered low melting point glass as an intermediate layer. Wafers can be bonded at room temperature with an applied voltage of about 50 V. This technique is useful for the fabrication of intelligent sensors and microelectromechanical systems.

The construction and performance of a hot-sphere-type anemometer

The hot-sphere-type anemometer is developed on the basis of the wire anemometer. The heated part of the sensor is a compact nicrome wire coil covered by a low melting point glass sphere. Inside the coil, there are one nicrome-constantan thermocouple or two in serial. This kind of sensor can produce higher potential than the ordinary hot wire anemometer and its heat inertia can be adjusted. The air velocity measured can be down to 0.05 m/sec. The instrument has sensitivity of ± 1.5% and its accuracy is within ±5.0%. It is stable and the effect of temperature and relative humidity variations is small.

The development of millimetre wave mixer diodes

A new format gallium arsenide beam lead diode has been developed which allows the total capacitance to be reduced sufficiently for applications throughout the millimetre waveband. The design involves the use of low melting point glass and has high mechanical strength for ease of handling. Metal-organic chemical vapour deposition has been used to provide the thin epitaxial layer required to minimize series resistance in the device. Typical measurements from many batches are total capacitance at zero bias 003 pF, including 002 pF stray capacitance, series resistance 6Ω and breaking force 4.5 g. The millimetre wave performance of the diodes has been demonstrated in microstrip mixer circuits operating at 90 GHz and 140 GHz. The microstrip single-ended mixer at 140 GHz extends the technology already established up to 100 GHz and includes a single crystal quartz substrate. The conversion loss of balanced mixers at 90 GHz is typically 6.5 dB and the single-ended mixer at 140 GHz displayed a loss of 7.0 dB.