• Journal of the Korean Ceramic Society
• /
• v.27 no.6
• /
• pp.783-789
• /
• 1990

Shaped crystal growth apparatus were made for sapphire ribbon single crystal growth. Sapphire ribbon single crystal are grown by EFG(Edge-defined Film-fed Growth) methdo for use as watch-glass and SOS(Silicon-On-Sapphire) devices. Sapphire ribbon crystals were grown to be 40min wide, 1.8mm thick, 96mm long. Therelationshiops between growth striation and surface roughness, with various growth rates, were investigated and compared. It was found that sapphire ribbon crystal is suitable for watch-glass by measuring the transmittance in the visible light region.

• Journal of Technologic Dentistry
• /
• v.25 no.1
• /
• pp.21-28
• /
• 2003

The purpose of this study was to process bio-active glass ceramic composite, reinforced with sapphire fibers, by hot press. Also to study the interface of the matrix and the sapphire fiber, and the mechanical properties. Glass raw materials melted in Pt crucible at 1300$^{\circ}C$ during 3.5 hours. The melt was crushed in ball mill and then crushed material, ground and sieved to $<40{\beta}{\mu}m$. Sapphire fibers cut (30mm) and aligned. Powder and fibers hot pressed. The micrographs show good bonding between the matrix and the fiber and no porosity in the glass matrix. This means ideal fracture phenomena. Glass is fractured before the fiber. This is indication of good fracture strength. EDXS showing aluminum rich phase and crystalline phase. Bright field image of the matrix showing crystalline phase. Also diffraction pattern of TEM showing the crystalline phase and more than one phase. Strength of the samples was determined by 3 point bend testing. Strength of the 10vol% sample was approximately 69MPa, while strength of the control sample is 35MPa. Conclusions through this study as follow: 1. Micrographs show no porosity in the glass matrix and the interface. 2. The interface between the fiber and the glass matrix show no gaps. 3. Fracture of the glass indicates characteristic fiber-matrix separation. 4. Presence of crystalline phase at high processing temperature. 5. Sapphire is compatible with bioactive glass.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.24 no.2
• /
• pp.224-230
• /
• 2015

In this study, the machinability of sapphire glass is tested using the powder blasting method under various blasting conditions. The thickness and diameter of the sapphire glass samples were 0.4 mm and 50.8 mm (2 inch), respectively. The machined patterns from each sample were a circle, a square, and a rectangle. The powder we used was GC #400 and #800. The blasting pressures of the powders were 2, 4, and 6 bar. The scanning time of the nozzle was 20 and the scanning speeds of the nozzle were 80, 100, and 120 mm/s. Experimental results showed that machining depths increased in proportion to blasting pressure. The machining depth of GC #800 was much higher than that of GC #400, while surface roughness was worst with GC #400. These results imply that the blasting pressure and size of the blasting powder are the most important parameters for machining sapphire glass.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2013.05a
• /
• pp.497-498
• /
• 2013

• Journal of Sensor Science and Technology
• /
• v.5 no.6
• /
• pp.68-73
• /
• 1996

ZnO thin films were prepared on glass and (012) sapphire substrates by rf magnetron sputtering. Polycrysralline ZnO films with a (002) orientation were obtained on glass substrates. (110) ZnO films were epitaxially grown on the (012) sapphire substrates. Surface acoustic wave properties were also measured for propagating along the c axis of ZnO film on the glass and sapphire substrates. The phase velocities ($V_{p}$) on glass and sapphire substrate at center frequency were 2680 m/sec and 5980 m/sec and the effective coupling coefficient ($k^{2}$) on the 0th mode were 0.98 % and 1.43 %, respectively.

• Tribology and Lubricants
• /
• v.32 no.2
• /
• pp.50-55
• /
• 2016

Recently, a double-side machining process has been adopted in fabricating a sapphire glass to enhance the manufacturability. Double-side lap grinding (DLG) is one of the emerging processes that can reduce process steps in the fabrication of sapphire glasses. The DLG process uses two-body abrasion with fixed abrasives including pallet. This process is designed to have a low pressure and high rotational speed in order to obtain the required material removal rate. Thus, the temperature is distributed on the DLG platen during the process. This distribution affects the shape of the substrate after the DLG process. The coolant that is supplied into the cooling channel carved in the base platen can help to control the temperature distribution of the DLG platen. This paper presents the results of computational fluid dynamics with regard to the heat transfer in a DLG platen, which can be used for fabricating a sapphire glass. The simulation conditions were 200 rpm of rotational speed, 50℃ of frictional temperature on the pallet, and 20℃ of coolant temperature. The five cases of the coolant flow rate (20~36 l/min) were simulated with a tetrahedral mesh and prism mesh. The simulation results show that the capacity of the generated cooling system can be used for newly developed DLG machines. Moreover, the simulation results may provide a process parameter influencing the uniformity of the sapphire glass in the DLG process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.29 no.3
• /
• pp.168-174
• /
• 2016

A conductive oxide-based sapphire glass indium tin oxide/metal electrode and the optical coating, through patterning process was studied in excellent optical properties and integrated touch panel has a high strength. Indium tin oxide conductive oxides of the sapphire glass to 0.3 A at DC magnetron sputtering method of 10 min, gas flow Ar 10 Sccm Ar, $O_2$ 1.0 Sccm the formation conditions of the thin film after annealing at $550^{\circ}C$ for 30min was achieved through a 86% transmittance. In addition, the coating 130 nm hollow silica sol-gel was to improve the optical transmittance of the indium tin oxide to 91%. For the measurement by the modeling hollow silica sol by Macleod simulation and calculated the average values of silica part to the presence or absence in analogy to actual. Refractive index value and the actual value of the material on the simulation the transmittance difference is it does not completely match the air region similar to the actual value (transmission) could be confirmed that the measurement is set to a value of between 5 nm and 10 nm.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2003.04a
• /
• pp.422-427
• /
• 2003

Sapphire have been ground by the ultra-precision surface grinder having a glass -ceramic spindle of extremely-low thermal expansion with various cup-type resinoid-bonded diamond wheels of #400-#3000 in grain size. Sapphire can be ground in the ductile mode. And also, the surface roughness and grinding conditions has been clarified. The smooth surface of Sapphire less than 1nm RMS, 1nm Ra can be obtained by the ultra-precision grinding without any polishing Process.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.640-643
• /
• 2003

We present investigations of the surface micromachining for transparent glass substrate, e.g. soda lime glass using tightly focused 800nm Ti:sapphire femtosecond laser. In this study, experiment conditions such as laser intensity, scanning speed, focus position were controlled as variable parameters to decide optimal machining conditions. This study shows clearly that laser intensity and scanning speed are dominant factors for good surface morphology. Using the optimal conditions, grooves with 50${\mu}{\textrm}{m}$ line width were fabricated on glass substrate and their surface morphologies were investigated from SEM image.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2009.11a
• /
• pp.27.1-27.1
• /
• 2009

In recent years, ZnO nanostructures have drawn considerable attentions for the development of futuristic electronic devices due to their superior structural and optical properties. As the growth of ZnO nanowires by MOCVD is a bottom-up technique, the nature of substrates has a vital role for the dimension and alignment of the nanowires. However, in the pursuit of next generation ZnO based nanodevices, it would be highly preferred if well-ordered ZnO nanowires could be obtained on various substrates like sapphire, silicon, glass etc. Vertically aligned nanowires were grown on A and C-plane sapphire substrates, where as nanopencils were obtained on R-plane sapphire substrates. In addition, C-axis oriented vertical nanowires were also found using an interfacial layer(aluminum nitride film) on silicon substrates. On the other hand, long nanowires were found on Ga-doped ZnO film on glass substrates. Structural and optical properties of the ZnO nanowires on various substrates were also investigated.