Abstract:
Processes and systems to reduce sticking of graphite materials and particularly resin impregnated graphite materials to forming tools, such as an embossing roller, during a process of manufacturing articles from the graphite materials. In one embodiment, an aerosol spray non-stick material is intermittently sprayed upon the embossing rollers. In a second embodiment, one or more sheets of thin flexible solid non-stick material, such as polyethylene, are sandwiched between the graphite material and the embossing rollers. The system is particularly useful for manufacturing material useful in producing components of fuel cells.
Abstract:
Processes are provided for formation of complex shapes by embossing of a sheet of flexible graphite material. In one approach, a sheet of material is provided with a variable resin concentration across its width, and the position of the variable resin concentration is correlated with the position of embossing features which will result in thinner areas in the embossed articles. In a second approach, recesses are provided in the embossing rollers to accommodate material flow during embossing. These recesses result in protrusions formed on the articles, which protrusions must then be removed in a machining operation.
Abstract:
Apparatus and methods are provided for the embossing of a sheet of flexible graphite material between a pair of embossing rollers. The embossing rollers include a primary embossing roller and a backup roller. The primary embossing roller has an embossing pattern defined thereon. One or both of the rollers include a raised stabilization area adjacent a periphery of the embossing pattern. The raised stabilization area preferably has a roughened outer surface for better gripping the sheet of flexible graphite material. The raised stabilization areas apply a stabilizing force to the sheet adjacent the periphery of the embossing pattern, thereby limiting egress of the material laterally away from the embossing pattern. The roughened surfaces increase the grip of the raised areas upon the sheet, thus aiding in pulling the sheet between the rollers and also aiding in the application of lateral stabilization forces to the sheet.
Abstract:
A substrate useful for the formation of, inter alia, a flow field plate for a proton exchange membrane fuel cell, the substrate formed of at least one resin-impregnated sheet of compressed particles of exfoliated graphite comprising two major surfaces, the substrate having an active area with flow field channels thereon, the sheet of compressed particles of exfoliated graphite having a local web thickness in at least about 50% of its active area that is no more than about 55% greater than the minimum web thickness of the active area of the substrate.
Abstract:
Processes are provided for formation of complex shapes by embossing of a sheet of flexible graphite material. In one approach, a sheet (26) of material is provided with a variable resin concentration across a selected dimension of the sheet, and the position of the variable which will result in thinner areas in the embossed articles. In a second approach, recesses are provided in the embossing rollers (30 and/or 32) to accomodate material flow during embossing. These recesses result in protrusions formed on the articles, which protrusions must then be removed in a machining operation.
Abstract:
A a substrate useful for the formation of, inter alia, a flow field plate for a proton exchange membrane fuel cell, the substrate formed of at least one resin-impregnated sheet of compressed particles of exfoliated graphite comprising two major surfaces, the substrate having an active area with flow field channels thereon, the sheet of compressed particles of exfoliated graphite having a local web thickness in at least about 50% of its active area that is no more than about 55% greater than the minimum web thickness of the active area of the substrate.
Abstract:
A graphite article comprising a compressed mass of graphite particles and a reactive lubricant, and a method of producing a graphite articles comprising a compressed mass of graphite particles and a reactive lubricant. The compressed mass of graphite particles may be impregnated with a lubricant and a resin. The lubricant may be a functionalized wax, fatty ester, silicone, or fatty acid. The lubricant may also be partially or fully fluorinated.
Abstract:
A process for preparing a gas permeable flexible graphite sheet is presented. The process includes providing graphite flakes; admixing the graphite flakes with a sacrificial additive to form a graphite mixture; compressing the graphite mixture into a sheet having sacrificial additive dispersed therethrough; and treating the sheet to at least partially remove the sacrificial additive to form a permeable flexible graphite sheet.