A Novel Tape and Diamond Process Developed for Polishing Hard Substrates

A nanoscale polish process with improved desired characteristics of low roughness and low scratch counts has been developed using a novel polish tape and diamond abrasive on hard glass substrates. For an improved polishing performance with high removal rate properties and preventing scratches, a novel tape was developed having a nanofiber level, densified surface and a flatter surface by slenderizing the fiber and dispersing ultrafine fiber using an innovative technique. Using this novel polishing tape with a fiber size of 200nm, one can produce a 17% lower surface roughness (Ra) (from 1.05A to 0.87A) and a reduced polished surface scratch count of 53 reduced to 18. The novel nanocluster diamond abrasive is synthesized from carbon atoms of explosives created by detonation in a closed chamber under an oxygen leaked atmosphere ambient. Several crystals are bonded together by layers of non-diamond carbon and other elements, forming aggregates with a nanocluster structure. Using this novel nanocluster diamond along with an ultra-fine diamond mixture with a nominal size of 15nm, one is able to produce an improvement of a 48% lower surface roughness Ra (from 0.87A to 0.45A) and a lower polishing surface scratch count reduced from 18 to 7. Overall, these results indicate that a smoother and a reduced scratch polished substrate results in a significant improvement in disk defects and related magnetic performances.

Comparison of the photoconversion of para-chlorophenol under simulated sunlight and UV irradiation in ice

The photochemistry of para-chlorophenol (4-CP) was studied under simulated sunlight (λ > 300 nm) and UV irradiation by using a 125 W high-pressure mercury lamp with or without a hard glass as light source in an ice matrix. The experiments were carried out in a photochemical cold chamber reactor at −14 to −12 °C. The photoconversion rate, photoproducts and photoconversion mechanism of 4-CP were all inspected and compared. The results show that the 4-CP photoconversion obeys the first order kinetic model and its photoconversion rate is highly affected by the initial concentration of 4-CP, light intensity and water quality. It is found that the conversion rate of 4-CP under UV irradiation is higher than that under simulated sunlight irradiation. The intermediate products of 4-CP were characterized by GC-MS, HPLC-ESI-MS and HPLC techniques and the possible photoconversion mechanism was proposed accordingly. It is concluded that the mechanism and photoproducts of 4-CP photolysis in ice are different from those in water, and the photoproducts and photoconversion pathways of 4-CP in ice varied with different light sources.