During the reporting period, work continued on development of formulations using the materials down-selected from the initially identified contenders for the fibrous monolith wear resistant components. In the previous reporting period, a two-stage binder removal process was developed that resulted in prototype parts free of voids and other internal defects. During the current reporting period, work was performed to characterize the two-stage binder removal process for WC-Co based FM material systems. Use of this process has resulted in the fabrication of defect free sintered WC-Co FM bodies, with minimal free carbon porosity and densities approaching 100% theoretical. With the elimination of free carbon porosity and other binder removal process related defects, development work focused on optimizing the densification and eliminating defects observed in WC-Co based FM consolidated by pressureless sintering. Shrinkage of the monolithic core and shell materials used in the WC-Co based FM system was measured, and differences in material shrinkage were identified as a potential cause of cell boundary cracking observed in sintered parts. Re-formulation of material blends for this system was begun, with the goal of eliminating mechanical stresses during sintering by matching the volumetric shrinkage of the core and shell materials. Thirty-three 7/8 inch drill bit …

During the reporting period, work continued on development of formulations using the materials down-selected from the initially identified contenders for the fibrous monolith wear resistant components. The FM systems studied were: WC-Co/WC-Co, WC-Co/Co, diamond/WC-Co, and Al{sub 2}O{sub 3}/Al{sub 2}O{sub 3}-TiCN. Extrudable formulations for the materials listed were developed during the first twelve months of this effort, and work during the reporting period was focused on the development of optimized binder removal processes. A two stage binder removal process was developed that resulted in prototype parts free of voids and other internal defects. In addition, changes in the binder removal atmosphere resulted in the apparent elimination of residual carbon, an important consideration when consolidating WC-Co containing systems. Using the improved binder removal processes, parts were consolidated by both sintering and hot pressing to >99% theoretical density. Samples of these materials were sent to Kyocera for mechanical evaluations. Fabrication of drill bit inserts was begun, and binder removal begun during the reporting period. A total of 24 green inserts were fabricated, and will be consolidated and delivered for field testing during the upcoming reporting period.

Published mechanical and thermal properties data on a variety of materials was gathered, with focus on materials that have potential with respect to developing wear resistant and damage tolerant composite for mining industry applications. Preliminary core materials of interest include but are not limited to: Diamond, Tungsten Carbide and Cemented Tungsten Carbides, Carbides of Boron, Silicon, Titanium and Aluminum, Diboride of Titanium and Aluminum, Nitrides of Aluminum, Silicon, Titanium, and Boron, Aluminum Oxide, Tungsten, Titanium, Iron, Cobalt and Metal Alloys. Preliminary boundary materials of interest include but are not limited to: W metal, WC-Co, W-Co, WFeNi, and Mo metal and alloys. Several FM test coupons were fabricated with various compositions using the above listed materials. These coupons were consolidated to varying degrees by uniaxial hot pressing, then cut and ground to expose the FM cell structure. One promising system, WC-Co core and WFeNi boundary, was consolidated to 97% of theoretical density, and demonstrates excellent hardness. Data on standard mechanical tests was gathered, and tests will begin on the consolidated test coupons during the upcoming reporting period. The program statements of work for ACR Inc. and its subcontractors, as well as the final contract negotiations, were finalized during the current reporting …

A set of materials property data for potential wear resistant materials was collected. These materials are designated for use as the ''core'' materials in the Fibrous Monolith structure. The material properties of hardness, toughness, thermal conductivity and cost were selected as determining factors for material choice. Data for these four properties were normalized, and weighting factors were assigned for each property to establish priority and evaluate the effects of priority fluctuation. Materials were then given a score based on the normalized parameters and weighting values. Using the initial estimates for parameter priority, the highest ranking material was tungsten carbide, with diamond as the second ranked material. Several materials were included in the trade study, and five were selected as promising ''core'' materials to include in this effort. These materials are tungsten carbide, diamond, boron carbide, titanium diboride and silicon carbide. Work was initiated on a trade study to evaluate ''shell'' materials. These materials will require the investigation of different material properties, including ultimate tensile strength, ductility, toughness, thermal expansion, thermal conductivity and compatibility during consolidation with the ''core'' materials. Kyocera Industrial Ceramics in Kyoto, Japan was visited, with the purpose of negotiating and signing the subcontract for Kyocera's participation on …