Application of microwave discharges for treatment of polymer surfaces
In this paper we analyze application of a simple microwave cavity discharge on the surface modification of polymers. Electrons and radicals from the low pressure plasma as well as the metastable excited oxygen species react intensively with many engineering plastic materials leading to the increased adhesion of polymers. This is of importance to achieve better bondability by gluing, painting, varnishing, stamping, printing or metalizing. The change of the wetting contact angle is discussed with respect to the treatment time and the polymer used. The creation of reactive functional groups of the hydroxyl and carboxyl acid type on the polymer surface is mainly responsible for the better adhesion. The lifetime of the bondability of polycarbonate, polymethyl methacrylate and polyether ketone was investigated. The surface modification of plastic materials may be performed in the vacuum chambers operated by low cost standar d microwave oven components or at a higher expense by rf generators at 13.6 MHz.
Microwave plasma: its characteristics and applications in thin film technology
Abstract Microwave plasmas differ significantly from other plasmas, exhibit many interesting properties and so offer new possibilities for the plasma processing of thin films. Plasma properties strongly depend on the conditions and methods used to excite the gas. Due to the existence of a direct connection between the properties of plasma-prepared thin films and plasma micro-parameters a perfect knowledge of the plasma generation is a basic requirement for mastering a plasma deposition process. Therefore, different methods of generating microwave isotropic and anisotropic plasmas are discussed. Special attention is devoted to the mechanisms of plasma excitation and to the generation of a dense and homogeneous plasma in large volumes. Some applications of microwave plasma in thin film technology are also presented.
Arc flash hazard assessment in the mining industry
When it comes to electrical safety in the workplace, arc flash has become the most prominent topic over the past decade. The Occupational Safety and Health Administration (OSHA, including state chapters) is the only government body that recognizes NFPA-70E, Standard for Electrical Safety in the Workplace. However, OSHA does not have jurisdiction in mining operations. Electrical safety for the metal and nonmetal surface mining industry is covered by the Code of Federal Regulations (CFR) Title 30, Part 56, Subpart K (Electricity). The Mine Safety and Health Administration (MSHA) is responsible for enforcing electrical safety in mining operations. CFR Title 30 does not reference personal protective equipment (PPE) to protect electrical workers against arc flash hazards. This paper provides maintenance and safety personnel in surface Metal/Nonmetal mining operations with a step by step guide to implementing an electrical safety program that meets the requirements of MSHA, CFR Title 30 and NFPA-70E.