Polytetrafluoroethylene Target Research Articles

Microfabrication of high quality polytetrafluoroethylene films by synchrotron radiation

We deposited polytetrafluoroethylene (PTFE) thin films both from the PTFE target by using synchrotron radiation (SR) beam and from PTFE emulsion by spin-coat process. The X-ray diffraction analyses showed a sharp peak due to (1 0 0) PTFE crystalline part, and only C–F 2 bonding was found in Fourier transform infrared spectrophotometer spectra. From electron spectroscopy for chemical analysis measurements, no impurities were found. The fabricated PTFE films were easily etched by SR beam on the limited area of the surface on a microscale through a suitably patterned mask.

PREPARATIONS AND INFRARED SPECTRUM STUDIES OF POLYTETRAFLUOROETHYLENE THIN FILMS

Polytetrafluoroethylene (PTFE) thin films have been grown successfully by rf magnetron sputtering technique. The infrared spectra of the as prepared films are consistent with those of the PTFE target. However, chains in the films become shorter than those in the bulk.

Formation of polytetrafluoroethylene thin films by using CO2 laser evaporation and XeCl laser ablation

Laser evaporation and laser ablation methods were applied to the preparation of polytetrafluoroethylene (PTFE) thin films. In the case of the laser evaporation method, PTFE targets were evaporated by a continuous wave (cw) CO2 laser (10.6 μm), and fluorocarbon thin films were formed at a deposition rate of as high as 2 μm/min for a laser power of 10 W. The chemical composition and structure of the deposited film corresponded to those of a PTFE target, which was confirmed by x-ray photoelectron spectroscopy and Fourier transform infrared absorption spectroscopy analyses. In the laser ablation method, PTFE targets were ablated by a XeCl excimer laser (308 nm). It is found that the deposited films contained a small amount of fluorine atoms on the surface. From these experiments, the successful formation of PTFE thin films was demonstrated for the first time using cw CO2 laser evaporation method.

Synchrotron radiation ablative photodecomposition and production of crystalline fluoropolymer thin films

Deposition of crystalline thin films of polytetrafluoroethylene (PTFE) was carried out on Si(100) substrates by synchrotron irradiation of a PTFE target in vacuo. In situ mass spectrometric analysis of gaseous species evolved during the irradiation shows that, different from the laser ablation of PTFE for the deposition, the SR-induced reactions should be ablative photochemical decomposition (APD) rather than photothermal unzipping decomposition, yielding saturated fluorocarbons rather than monomers as the main gaseous products. Detection of a trace of CF3 in the deposited films by XPS and FTIR was consistent with our APD mechanism. In our processing, an increase in the target temperature made great improvements including considerable enhancement of the deposition rates, reduction of the CF3 component, and achievement of the crystalline features closer to the PTFE target, whereas an increase in the substrate temperature made the film surface rough.

Laser Ablation and the Production of Polymer Films

The formation of high-quality thin films of polytetrafluoroethylene (PTFE) is important in many applications ranging from material reinforcement to molecular electronics. Laser ablation, a technique widely used to deposit a variety of inorganic materials, can also be used as a simple and highly versatile method for forming thin polymer films. The data presented show that PTFE films can be produced on various supports by the evaporation of a solid PTFE target with a pulsed ultraviolet laser. The composition of the ablation plume suggests that PTFE ablation and subsequent film formation occur by way of a laser-induced pyrolitic decomposition with subsequent repolymerization. The polymer films produced by this method are composed of amorphous and highly crystalline regions, the latter being predominantly in a chain-folded configuration with the molecular axis aligned parallel to the substrate surface.

Radio frequency sputtering process of a polytetrafluoroethylene target and characterization of fluorocarbon polymer films

Fluorocarbon polymer films have been deposited on glass, silicon, and carbon substrates by radio frequency (rf) sputtering of a polytetrafluoroethylene (PTFE) target in pure argon and Ar–C3F8 mixtures using either a conventional sputtering mode or a self-sustaining glow discharge mode. The substrates could be isolated from the plasma region by a grounded grid electrode. The deposition rate of films produced on glass and silicon substrates was measured as a function of the gas composition and total pressure. The grounded grid electrode effect on the deposition rate of films was also investigated. The polymer films were characterized by x-ray diffraction, infrared spectroscopy, and Rutherford backscattering spectroscopy. The morphology of films was examined before and after annealing at 450 °C in pure argon ambient for 4–24 h. The optimum deposition conditions to produce (CFx)n polymer films with high fluorine contents and high deposition rates by rf sputtering of a PTFE target are reported and discussed in the article.

Cathodic sputtering for preparation of lubrication films

In order to investigate their lubricating behaviour, thin films of MoS x , CF x and CaF 2 were prepared by cathodic sputtering: d.c. reactive magnetron sputtering of a molybdenum or MoS 1.6 target in an Ar-H 2S atmosphere for MoS x films; r.f. diode sputtering of a polytetrafluoroethylene target in an argon or Ar-C 3F 8 atmosphere for CF x films and of a CaF 2 target in an argon atmosphere for CaF 2 films. The properties of the films (morphology, structure, composition, hardness, density, friction coefficient and wear) were investigated in relation to the deposition parameters. Adherent and dense films were deposited on stainless steel substrates. The thickness ranged from 0.5 to 28 μm for MoS x films, from 0.5 to μm for CF x films and from 0.2 to 4 μm for CaF 2 films. The MoS x layers present a hexagonal structure with various preferred orientations, the CaF 2 layers are cubic with a (111) preferred orientation, while the CF x coatings are amorphous. Numerous tribology tests were performed on MoS x films in dry air or nitrogen. Minimum friction coefficients of 0.025 (pin on disk) and 0.01 (collar axle) were found for MoS 1.5-1.7 films exhibiting a (001) preferred orientation and a hardness of 5000 MPa. The best wear results were observed for MoS 1.8 films exhibiting a hardness of 2000 MPa. Other experiments were carried out in liquid nitrogen. Finally, the film behaviour in humid air was analysed. Tribology test conditions for CF x and CaF 2 are being optimized.