Structure and phase formation of ion-plasma vacuum-arc Zr-B-Si-C-Ti-(N) coatings during deposition

Zr-B-Si-C-Ti-N and Zr-B-Si-C-Ti coating systems were produced by arc-PVD technique. For their deposition, a combined titanium cathode with a ZrB2-SiC insert was used. Deposition was carried out in a residual atmosphere of N2 and Ar. Coatings structure and composition were investigated. The Zr-B-Si-C-Ti coating is characterized by an amorphous-nanocrystalline structure. In this case, nanocrystallites were formed from complex (Zr, Ti) C, and the amorphous structure fraction is formed mainly by phases based on zirconium and silicon. The second system, deposited in a nitrogen residual atmosphere, Zr-B-Si-C-Ti-N, has a predominantly amorphous structure. Such a structure is formed mainly from borides, nitrides, carbides and complex compounds of zirconium, silicon and titanium.

Электроды вакуумной камеры под действием дуги в зоне взрывного плавления

The floatable systems Cu (60%) - Cr (40%) after repeated influence of the arc vacuum discharge find change of atomic concentration of copper (with 53.7 ат. % to 71.8 ат. %) and, respectively, chromium. The mass-spectrometry showed existence in the residual atmosphere of diffusion instruments fragments of the CxHy molecules and molecules desorbed from all details of the camera, ions of residual gas (CO2, H2O, N2, N and their polyatomic compositions). Inheritance of technological impurity from prior operations in a mass spectrum is revealed.

Вклад газов остаточной атмосферы в поток коллективно ускоренных протонов в диоде Люса

Contribution of gases of residual atmosphere on number of protons collectively accelerated in Luce diode was determined by comparison of the number of protons generated with polyethylene and boron nitride anodes. The proton average number and energy were determined by a use of the radioactivation diagnostics via nuclear reactions 10B(p,α)7Be and 12C(p,γ)13N. It was found that the number of protons collectively accelerated due to adsorption of water vapors and hydrocarbons from the residual camera atmosphere can be comparable with the number of protons accelerated due to sublimation of surface of the polyethylene anode.

Low Earth Orbital Atomic Oxygen Interactions with Spacecraft Materials

ABSTRACTAtomic oxygen, formed in Earth's thermosphere, interacts readily with many materials on spacecraft flying in low Earth orbit (LEO). All hydrocarbon based polymers and graphite are easily oxidized upon the impact of ∼4.5 eV atomic oxygen as the spacecraft ram into the residual atmosphere. The resulting interactions can change the morphology and reduce the thickness of these materials. Directed atomic oxygen erosion will result in the development of textured surfaces on all materials with volatile oxidation products. Examples from space flight samples are provided. As a result of the erosive properties of atomic oxygen on polymers and composites, protective coatings have been developed and are used to increase the functional life of polymer films and composites that are exposed to the LEO environment. The atomic oxygen erosion yields for actual and predicted LEO exposure of numerous materials are presented. Results of in-space exposure of vacuum deposited aluminum protective coatings on polyimide Kapton indicate high rates of degradation are associated with aluminum coatings on both surfaces of the Kapton. Computational modeling predictions indicate that less trapping of the atomic oxygen occurs, with less resulting damage, if only the space-exposed surface is coated with vapor deposited aluminum rather than having both surfaces coated.