Improvement of preferred orientation of NiAl/CrMn underlayers deposited on prebaked tape substrates
It was observed that the coercivity of CoCrPt films deposited on a polyimide tape was much lower than the coercivity deposited on a rigid glass substrate under identical conditions. X-ray diffraction showed that the desirable (112) and (110) texture of the NiAl/CrMn underlayers on the tape substrate was severely degraded during the deposition process. This resulted in the destruction of (10.0) growth texture of CoCrPt films and a significant reduction of magnetic coercivity. However, degassing of the tape substrate under vacuum before deposition significantly enhanced the magnetic properties. The coercivity of the film reached 170 kA/m which is near that achieved on a glass substrate. Auger analysis also revealed that oxygen was present in the NiAl/CrMn underlayers deposited without degassing the tape substrate.
Recording properties of CoCrPt tape media sputter-deposited at room temperature on polymeric substrates
Recording properties of CoCrPt thin films sputter-deposited on polymeric substrates at room temperature were investigated. Typical frequency spectra of the readback signal from sputtered tapes at various recording densities revealed an appreciable amount of modulation noise, despite the fact that the sputtered tape is expected to be smooth and conformal with the substrate. Atomic force microscopy images suggest the modulation noise, present as side bands about the signal peak, is primarily due to the roughened polymeric substrate. The nonlinear partial erasure method was used to measure the sharpness of recorded transitions via the frequency domain one-dimensional/three-dimensional method. Intertransition interactions occurred at a linear density of 130 kfci, which corresponds to a transition length parameter (πa) of 195 nm. This rather large value of transition length is attributed to exchange coupling between grains in the media, suggesting inadequate Cr segregation due to the low-temperature deposition...
Preparation of hydrophilic poly(vinyl butyral) hollow fiber membrane via thermally induced phase separation
Abstract Hydrophilic microporous hollow fiber membranes were prepared via thermally induced phase separation (TIPS). Poly(vinyl butyral) (PVB) and three kinds of polyethylene glycols (PEG) with the molecular weight of 200, 400 and 600 were used as polymer and diluents. In all cases, liquid–liquid (L–L) phase separation occurred and asymmetric cellular structures with the smaller pores at the outer surface were obtained. The properties of membranes such as pore size, water permeability, solute rejection and intensity were investigated by changing molecular weight of PEG, concentration of PVB, composition of the bath and air gap distance. The smaller molecular weight of PEG, the more PEG in the bath and the shorter air gap distance resulted in the higher water permeability, the lower solute rejection property and the lower mechanical strength.