• Nuclear Engineering and Technology
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• v.51 no.4
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• pp.1069-1074
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• 2019

A novel fabrication method of oxide dispersion strengthened (ODS) steel cladding tubes for advanced fast reactors has been investigated using the cold spray powder-based materials deposition process. Cold spraying has the potential advantage for rapidly fabricating ODS cladding tubes in comparison with the conventional multi-step extrusion process. A gas atomized spherical 14YWT (Fe-14%Cr, 3%W, 0.4%Ti, 0.2% Y, 0.01%O) powder was sprayed on a rotating cylindrical 6061-T6 aluminum mandrel using nitrogen as the propellant gas. The powder lacked the oxygen content needed to precipitate the nanoclusters in ODS steel, therefore this work was intended to serve as a proof-of-concept study to demonstrate that free-standing steel cladding tubes with prototypical ODS composition could be manufactured using the cold spray process. The spray process produced an approximately 1-mm thick, dense 14YWT deposit on the aluminum-alloy tube. After surface polishing of the 14YWT deposit to obtain desired cladding thickness and surface roughness, the aluminum-alloy mandrel was dissolved in an alkaline medium to leave behind a free-standing ODS tube. The as-fabricated cladding tube was annealed at $1000^{\circ}C$ for 1 h in an argon atmosphere to improve the overall mechanical properties of the cladding.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.6
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• pp.91-97
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• 2018

Chemical mechanical polishing(CMP) realizes a surface planarity through combined mechanical and chemical means. In CMP process, Preston equation is known as one of the most general approximation of the removal rate. Effects of pressure and relative speed on the mechanical property of Cu CMP has been investigated. On the other hand, The amount of abrasion also increased with changes in pressure and speed, resulting in a proportional increase of temperature during CMP. Especially this temperature is an important factor to change chemical reaction in a Cu CMP. However, when the slurry temperature became higher than $70^{\circ}C$, the removal rate went lower due to abrasives aggregation and scratching occurred on the Cu film. Therefore, it was found that the slurry temperature should not exceed $70^{\circ}C$ during Cu CMP. Finally, authors could increase the pressure, speed and slurry temperature up to a ceratin level to improve the removal rate without surface defects.

• Tribology and Lubricants
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• v.40 no.2
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• pp.67-70
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• 2024

Chemical mechanical planarization (CMP) is an essential process for ensuring high integration when manufacturing semiconductor devices. CMP mainly requires the use of polyurethane-based polishing pads as an ultraprecise process to achieve mechanical material removal and the required chemical reactions. A diamond disk performs pad conditioning to remove processing residues on the pad surface and maintain sufficient surface roughness during CMP. However, the diamond grits attached to the disk cause uneven wear of the pad, leading to the poor uniformity of material removal during CMP. This study investigates the pad wear rate profile according to the swing motion of the conditioner during swing-arm-type CMP conditioning using deep learning. During conditioning, the motion of the swing arm is independently controlled in eight zones of the same pad radius. The experiment includes six swingmotion conditions to obtain actual data on the pad wear rate profile, and deep learning learns the pad wear rate profile obtained in the experiment. The absolute average error rate between the experimental values and learning results is 0.01%. This finding confirms that the experimental results can be well represented by learning. Pad wear rate profile prediction using the learning results reveals good agreement between the predicted and experimental values.

• Proceedings of the KACD Conference
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• 2001.11a
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• pp.577-577
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• 2001

The lastest concepts in bonding are "total etch", in which both enamel and dentin are etched with an acid to remove the smear layers, and "wet dentin" in which the dentin is not blown dry but left moist before application of the bonding primer. Ideally, the application of a bonding agent to tooth structure should be insensitive to minor contamination from oral fluids. Clinically contaminations such as saliva, gingival fluid, blood and handpiece lubricant are often encountered by dentists during preparation of a restoration. The aim of this study was to evaluate the effect of contamination by hem-ostatic agents on shear bond strength of compomer restorations. One hundred and ten extracted human maxillary and mandibular molar teeth were collected. The teeth were cleaned from soft tissue remnant and debris and stored in physiologic solution until they were used. Small flat area on dentin of the buccal surface were wet ground serially with 400, 800 and 1200 abrasive paper on automatic polishing machine. The teeth were randomly divided into 11 groups. Each group was conditioned as follows: Group 1 : Dentin surface was not etched and not contaminated by hemostatic agents. Group2 : Dentin surface was not etched but was contaminated by Astringedent (Ultradent product Inc., Utah, U.S.A.). Group3 : Dentin surface was not etched but was contaminated by Bosmin (Jeil Phann, Korea.). Group4 : Dentin surface was not etched but was contaminated by Epri-dent (Epr Industries, NJ, U.S.A.). Group5: Dentin surface was etched and not contaminated by hemostatic agents. Group 6 : Dentin surface was etched and contaminated by Astringedent. Group7 : Dentin surface was etched and contaminated by Bosmin. Group8 : Dentin surface was etched and contaminated by Epri-dent. Group9 : Dentin surface was contaminated by Astringedent. The contaminated surface was rinsed by water and dried by compressed air. Group10 : Dentin surface was contaminated by Bosmin. The contaminated surface was rinsed by water aud dried by compresfed air. Group 11 : Dentin surface was contaminated by Epri-dent. The contaminated surface was rinsed by water and dried by compresfed air. After surface conditioning, F2000 was applicated on the conditoned dentin surface. The teeth were thermocycled in distilled water at $5^{\circ}C\;and\;55^{\circ}C$ for 1000 cycles. The samples were placed on the binder with the bonded compomer-dentin interface parallel to the lmife-edge shearing rod of the Universal testing machine(Zwick 020, Germany) running at a cross head speed of 1.0mmimin. There were no significant differences in shear bond strength between groups 1 and group 3 and 4, but group 2 showed significant decrease in shear bond strength compared with group 1. There were no significant differences in shear bond strength between group 5 and group 7 and 8, but group 6 showed significant decrease in shear bond strength compared with group 5. There were no significant differences in shear bond strength between group 5 and group 9, 10 and 11.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.2
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• pp.182-190
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• 2007

Statement of problem: Titanium has many advantages of high biocompatibility, physical properties, low-weight, low price and radiolucency, but it is incompatible with conventional dental porcelain due to titanium's oxidative nature. Many previous studies have shown that they used the method of sandblast for surface treatment prior to porcelain application, the researches are processing about the method of acid etching or surface coating. Purpose: The purpose of this research is to study the effect on bond strength of surface roughness between titanium and porcelain with the same surface topography. Material and method: In this study, we evaluated the bond strength by using 3-point bending test based on ISO 9693 after classified 8 groups - group P : polished with #1200 grit SiC paper, group S10 : $1.0{\mu}m$ surface roughness with sandblasting, group S15 : $1.5{\mu}m$ surface roughness with sandblasting, group S20 : $2.0{\mu}m$ surface roughness with sandblasting, group S25 : $2.5{\mu}m$ surface roughness with sandblasting, group S30 : $3.0{\mu}m$ surface roughness with sandblasting, group S35 : $3.5{\mu}m$ surface roughness with sandblasting, group E : $1.0{\mu}m$ surface roughness with HCl etching. Results: Within the confines of our research, the following results can be deduced. 1. In the results of 3-point bending test, the bond strength of sandblasting group showed significant differences from one of polishing group, acid etching group(P<.05). 2. The bond strength of sandblasting groups did not show significant differences. 3. After surface treatments, the group treated with sandblasting showed irregular aspect formed many undercuts, in the SEM photographs. The bond strength of sandblasting group was higher than 25 MPa, the requirement of ISO 9693. Conclusion: In above results, bond strength of titanium and low-fusing porcelain is influenced more to surface aspect than surface roughness. And titanium has clinically acceptable bond strength below surface roughness of $3.5{\mu}m$.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.8
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• pp.21-28
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• 2008

Fizeau interferometer is used for inspecting the lens surface profile accurately. This study is focused on the design and optical measuring techniques for large optical components, such as a reflection mirror for large area lithography or astronomical purpose. A tower type Fizeau interferometer is designed and set up in horizontally with a 45$^{\circ}$ fold mirror which makes easy to align the optical path of heavy interferometer system. To align the optical path, a five-axes stage for the interferometer is required. This study shows a method of the 45$^{\circ}$ fold mirror alignment by using a three-axis stage instead of adjusting the interferometer itself or measuring object. This system will be installed on the large optics polishing machine during the manufacturing process as an on-machine inspection system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.276-276
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• 2009

Solar cells has been studied mainly the high efficiency and lower prices. Using recycling wafer as a way to realize their money in it, there is a way to manufacture a solar cell substrate. How to play the recycling wafer, CMP(Chemical Mechanical Polishing) and remelting process is the complex and the expensive equipment. However, using the Micro-Blaster, the process easier, and cheaper prices. Micro-Blaster confirmed that the remaining amount of material left after the process recycling wafer surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.482-483
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• 2009

In chemical mechanical planarization (CMP) process, the uniformity of stress acting on wafer surface is a key factor for uniform material removal of thin film especially in the oxide CMP. In this paper, we analyze the stress on the contact region between wafer and pad with finite-element analysis (FEA). The setting pressure acting on wafer back side was $500g/cm^2$ and the retainer pressure was changed from 300 to $700g/cm^2$. The polishing test is also done with the same conditions. The material removal rate profiles well-matched with stress distribution.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.1
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• pp.61-70
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• 2004

Generally, ceramics are very difficult-to-cut materials because of its high strength and hardness. The machining process of ceramics can be characterized by cracking and brittle fracture. In the machining of ceramics, edge chipping and crack propagation are the principal reasons to cause surface integrity deterioration. Such phenomenon can cause not only poor dimensional and geometric accuracy, but also possible failure of the ceramic parts. Ceramics can be machined with traditional method such as grinding and polishing. However, such processes are generally cost-expensive and have low material removal rate. Thus, in this paper, to overcome these problems. BN powder, which gives good cutting property, is added for the fabrication of machinable ceramics by volume of 5,10,15,20,25 and 30%. And, mechanical properties, R-curve behavior and machining tests are carried out to evaluate the machining properties of the manufactured machinable ceramics.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.240-247
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• 2002

The rolling wear behavior of SM55C is investigated under lubrication. This is a comparative tribological behavior of heat treatment effect for SM55C. Rolling wear test method is used for Ball-on-disk type. Specimens can be classified into two main groups: as-annealing and non-annealing. As result of wear behavior, flanking initial time of non-annealing specimen keep at retard but it have not under high normal load. One of the notable features of annealing specimen is steady flanking initial time for a normal load in this experiment. Failure mechanism of SM55C is due to the fatigue wear such like flanking, pitting etc.. Flanking leads to abruptly fracture of worn surface. Fracture mechanism has a connection with normal load and polishing direction of specimens.