Air force 17. 1 Small Business Innovation Research (sbir) Phase I proposal Submission Instructions

PHASE II: Advance the Phase I formulations and processes to improve the powder coating removal consistent with MIL-PRF-24712 performance specifications. Demonstrate that these materials and processes can be used as a drop-in replacement for current coating removal processes being used. Develop a draft specification.

PHASE III DUAL USE APPLICATIONS: Military Application: Evaluate selected formulation and processes vs. currently approved coating removal methods per T.O. 1-1-8. Perform coating removal testing and verify powder coating removal capability; revise formulation as necessary.

REFERENCES:

1. T.O. 1-1-8, Application and Removal of Organic Coatings, Aerospace and Non-Aerospace Equipment.

2. T.O. 35-1-3, Corrosion Prevention and Control, Cleaning, Painting, and Marking of USAF Support Equipment (SE).

KEYWORDS: blast media, cleaning, materials, mechanical removal equipment, nano-materials, powder coatings

TECHNOLOGY AREA(S): Air Platform

OBJECTIVE: Develop a corrosion model which tracks aircraft environmental exposure using off-board sensors and produces a corrosion severity index which can be used to adjust the corrosion related maintenance activities based upon the condition of the aircraft.

DESCRIPTION: The USAF expends a large amount of resources on corrosion related maintenance and is seeking ways to reduce the resource burden with little to no impact on performance. One potential area for improvement is aircraft wash frequency. Current USAF wash intervals are dictated by TO 35-1-3 (support equipment) and TO 1-1-691 (aircraft). The technical orders correlate wash intervals with the environmental severity of the assigned location of the asset. Aircraft assigned to a specific geographic location do not exclusively operate in that location. Operational mission assignments frequently drive aircraft away from their assigned location and potentially into a different environment. Differences in aircraft usage can also drive different rates of corrosion. Not all aircraft assigned to the same base see the same usage. Some aircraft will experience a higher operational tempo than others. The current technical orders do not take into account asset usage when determining wash intervals. Additionally, support equipment environments can change based upon asset storage conditions. Some equipment may be stored indoors while other equipment is stored primarily outdoors. Another concern is the fact that environmental conditions are not constant and vary over time. The environmental severity categories that are included in the technical orders are based on a long term measurement of the environment at the location. This static approach does not take into account transient changes in the weather which could have a large impact on the environmental severity at any given location.

The USAF seeks to develop a corrosion model which incorporates asset environmental exposure (duration, location, season, weather, pollutants) as inputs to produce a cumulative corrosion severity or damage metric. The environment can be characterized using off-board sensors or other available data (weather, atmospheric, etc.) from reputable sources. The actual location of assets can also be determined from current USAF data systems. The fusion of actual environment and location data can yield an asset level corrosion severity index. The cumulative corrosion damage metric would be used to adjust equipment wash intervals based upon the specific condition of the equipment which would be a result of the actual environmental conditions the equipment has been exposed to. The potential exists to expand the scope of this methodology beyond wash intervals and eventually control all scheduled corrosion related maintenance activities based on of the asset level corrosion severity index. An ideal model framework will have sound scientific underpinnings based on materials behavior, be extensible in follow on efforts to include additional factors that might arise in specific situations (or be omitted if not relevant to a particular application), and support a path to implementation including integration with available resources and assets. Time-independent methods that do not consider environmental fluctuations are not of interest in this solicitation.

PHASE I: Identify critical environmental and asset usage factors contributing to corrosion. Develop model to predict a cumulative corrosion severity based on exposure and asset usage inputs. Quantitative measurements of corrosion selected by the contractor shall have a correlation coefficient (R-squared) between predicted and observed results of at least 0.75 in previously demonstrated applications to be considered competitive. Select COTS sensor suite to monitor identified off-board environmental parameters as well as on- board sensors to support model validation.

PHASE II: Develop plan for adjusting aircraft wash and inspections based upon model outputs. Demonstrate correlation of observed and predicted corrosion results on models developed in Phase 1 for at least a one year time period. Develop aircraft tracking application to use all available LIMS-EV data as an input and produce an accurate history of aircraft location. Integrate aircraft location data into corrosion severity index model. Procure and install off-board environmental sensor package at selected pilot locations.

PHASE III DUAL USE APPLICATIONS: Implement & use corrosion severity index model on B-1 & C-5 systems to determine aircraft wash intervals & other field level corrosion related inspections. Validate model using small group of B-1 & C-5 aircraft and related support equipment and ensure the model correlates with on-board measurements.

REFERENCES:

1. Abbott, W. H., Pate, Henry O., and Fernandez, Felix, “Acceleration Factors for Severe Outdoor Exposures vs. Flight on Military Aircraft,” available atwww.corrdefense.org.

2. Morefield, S., Drozdz, S.A., Hock, V.F., Abbott, W.H., Paul, D., and Jackson, J.L., “Development of a Predictive Corrosion Model Using Locality-Specific Corrosion Indices”, final report, ERDC/CERL TR-09-22, August 2009.

3. Rose, D.H.,"A Cumulative Damage Approach to Modeling Atmospheric Corrosion of Steel”, Ph.D. dissertation, University of Dayton, 2014.

4. Summitt, R. and Fink, F.T., “PACER LIME: An Environmental Corrosion Severity Classification System”, AFWAL-TR-80-4102 Part 1, August 1980.

5. Summitt, R. and Fink, F.T., “PACER LIME: Part II – Experimental Determination of Environmental Corrosion Severity”, AFWAL- TR-80-4102 Part 1, June 1980.

KEYWORDS: aircraft environmental exposure, aircraft wash intervals, corrosion, corrosion model, corrosion severity index, predictive, CBM+, model

AF171-096

TITLE: Improved Casting Quality through Novel Engineered Ceramic Molten Metal Filters Improved Casting Quality through Additively Manufactured Ceramic Molten Metal Filters

TECHNOLOGY AREA(S): Materials/Processes

OBJECTIVE: Incentivize small businesses to utilize advances in ceramic manufacturing, including, but not limited to, additive manufacturing, to develop new and/or improved ceramic filters used in metal casting processes leading to significantly cleaner and less porous castings

DESCRIPTION: Aerospace and commercial metal casters utilize ceramic filters to insure clean uncontaminated metal flows into the mold. One of the most common filters is made from reticulated ceramic foam. Current ceramic foam filter designs produce significant variation in metal flow rate and do not always remove 100% of contaminants. A published study (1) of foam filters found a significant variation in filtration efficiency. For a single, typically used grade (i.e., pore size) of ceramic foam filter the average filtration efficiency was only 69%. More concerning, the piece-to-piece measured filtration efficiency varied between 21 and 93%. In another published study (2), the authors evaluated the physical structure of reticulated ceramic foam filters from the four largest filter manufacturers. For this same typically used filter grade, the supplier-to-supplier variation in pore diameters for filters with an average filter pore diameter of 2126 microns was 578 microns. In a further study of filter efficiency (3) the authors found, as expected, that when the incoming metal was relatively clean (i.e., low levels of small inclusions), improved filtration occurred using finer filter grades, but they also noted individual filter performance was significantly influenced by variations in the physical properties of the filter. Finer filter grades require increased metal priming height and can easily clog leading to disruptions in metal flow and undesirable casting porosity. In critical aerospace applications where a tree of parts is simultaneously cast with a filter in each individual cavity, filter-to-filter differences in permeability can result in unpredictable differences in individual cavity fill times. The better solution would be to develop a more consistent ceramic filter. What is required is a range of filter sizes consistent with current commercial filter grades 30 through 80 that show permeability repeatability within 5% filter-to-filter.

Ceramic filters used in metal casting must meet a number of requirements. They must be mechanically strong enough to survive assembly into the mold and metal pouring, and they must be chemically resistant to molten metals and thermally shock resistant to the mold burn out and casting process. Efficient filters must have a large surface area and act as a getter material that can attract and retain nonmetallic inclusions and contaminants. Most important, they must have a predictable porosity that produces a consistent and controllable permeability. For current ceramic foam filters meeting the latter requirement is the most challenging as the filters are produced from a highly-random, reticulated polymeric foam precursor infiltrated with ceramic slurry. Thus, ceramic foam filters are sold based upon pore density (pores/inch) and not permeability.

Advances in ceramic manufacturing, including additive manufacturing techniques, have made it possible to produce very repeatable parts with highly engineered internal structures. The USAF is looking to improve metal casting processes through the use of improved manufacturing to develop and demonstrate step change improvements in ceramic molten metal filter design and manufacturing.

PHASE I: Develop prototype filter designs and produce sample filters. Flow test prototypes demonstrating a range of filter permeability consistent with current commercial foam filter grades 30 through 80. Demonstrate filter-to-filter statistical repeatability of permeability. Should complete at least one metal pour demonstrating filter survivability. Provide an initial cost/benefit analysis.

PHASE II: Further investigate filter designs to optimize performance. Work with aerospace caster producing typical aerospace alloy pours. Demonstrate multiple, engineered filter designs resulting in robust mechanical properties, predictable metal flow rate, and statistical significant improvement in casting cleanliness/porosity with no deleterious casting impact. Key process parameters understood with demonstrated capability to produce prototypes in manufacturing relevant environment. Update cost/benefit analysis.

PHASE III DUAL USE APPLICATIONS: Work with one or more aerospace casters demonstrating use of designed filters on a range of critical investment castings supplied for use on the latest generation fighters and tankers. Work with industrial metal casters to explore implementation and qualification on select commercial applications.

REFERENCES:

1. N. J. Keegan, W. Schneider, H. P. Krug, “Efficiency and Performance of Industrial Filtration Systems”, 6th Australasian Pacific Course and Conference, Aluminum Casthouse Technology: Theory and Practice (ED: M Nilmani, TMS 1999, pp 159 -174.

2. Steven F. Ray, “Recent Improvements in the Measurement and Control of Ceramic Foam Filter Quality”, Presented at the International Melt Quality Workshop, Madrid, Spain, 25-26 October 2001.

3. N. J. Keegan, W. Schneider, H. P. Krug, “Evaluation of the Efficiency of Fine Pore Ceramic Foam”, Light Metals 1999, pp 1031 – 1041.

KEYWORDS: additive, casting, ceramic, filters, manufacturing, metal

TECHNOLOGY AREA(S): Materials/Processes

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with section 5.4.c.(8) of the solicitation and within the AF Component-specific instructions. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. Please direct questions to the AF SBIR/STTR Contracting Officer, Ms. Gail Nyikon, gail.nyikon@us.af.mil.

OBJECTIVE: Develop and demonstrate a high temperature moisture sealant to go over the ceramic coatings on existing turbine engine exhaust system ceramic of the advanced fleet. The coating and its application methods should be suitable for production, depot, and field repair.

DESCRIPTION: High temperature exhaust coatings are used for improved survivability in a variety of advanced aircraft engine exhaust applications, but they often have limited durability due to moisture effects. Their importance for aircraft safety and warfighter dominance cannot be understated. By weight, these coatings on advanced aircraft correspond to < 1 %, but they are often in the top 3 maintenance drivers on an annual basis with extensive downtimes and inspection protocols, not to mention severely limiting logistics and planning. These coatings are typically somewhat porous, often being air plasma sprayed or electron beam deposited, and may have spalling issues due to moisture exposure and reaction (causing cohesion failures at 25% of their design life).

The goal of this effort is to identify and optimize a high temperature sealant chemistry that could be applied over the existing exhaust coating without causing knockdowns in coating performance but provide better life due to moisture resistance. Some studied sealant systems are provided in the references. The application method and cure method for these sealants will be important because only the exterior of the exhaust panel needs to be sealed and not the panel sides or back face. So characterization of the sealant thickness, its uniformity and ability to be applied to a single side of an exhaust panel will be important and will need to be assured via SEM and possible TEM analysis. The offerer will also need to demonstrate the benefit of the high temperature sealant against repeated moisture exposures via a series of thermal, mechanical, and electrical tests (these tests are usually defined by the prime engine manufactures). For example it has been shown in the past by four point bend test and cantilever bend test that when the coated exhaust panels are exposed to 10 wet/dry cycles (16 hr soak followed by 150°F dry) that their modulus is increased by 2X and their strain to failure decreased by 2X resulting in a cohesive coating failure. Additionally, a coated, sealed and exposed panel then needs to pass a temperature durability test via cyclic burner rig testing (usually 2000 to 4000 cycles at 1800°F). Finally the panels will need to go to an environmental burner rig testing which combines both moisture exposure and burn rig testing sequentially until failure occurs. The electrical testing needs to be defined and conducted by an engine prime contractor. It is also important to remember that another focus of this effort is on a simple application method that could be employed at the part manufacturing facility, at repair depots and also in the field on large components. Teaming with an engine OEM is highly recommended for insight into coating characteristics, operating conditions, and performance requirements.

PHASE I: Explore sealant chemistry, application methods, and heat treatment cure requirements. Demonstrate feasibility of the sealant via limited characterization using bend testing screening methods on coated, sealed, and moisture exposed substrates purchased from an OEM or their coating vendor. No government equipment or supplies will be available to the program.

PHASE II: Optimize sealant chemistry, application method, and heat treatment to assure uniform coverage without pore close-off which increases to modulus. Have the sealant applied at the OEM facility on their proprietary materials. Have the OEM conduct cyclic burner rig testing, environmental burner rig testing and electrical testing on the coupons.

PHASE III DUAL USE APPLICATIONS: Contractor complete qualification testing and transition the technology to an engine OEM end user and/or maintenance depot.

REFERENCES:

1. "Protective Coatings and Thin Films" by Y. Pauleau and P.B. Burma @https://books.google.com/books id=ApTI7h7Db2UC&printsec=frontcover#v=onepage&q&f=false

2. "Engineering Materials Handbook : Adhesives and Sealants" by ASM International Handbook Committee 1990 @https://books.google.com/books?id=kb0RAQAAMAAJ&q=Thin+film+moisture+resistant+sealants+for+high+temperature+ceramic+coatings&dq=Thin+film+moisture+resistant+sealants+for+high+temperature+ceramic+coatings&hl=en&sa=X&ved=0ahUKEwiY nY3Q0ZDMAhXJOyYKHfX2DfoQ6AEINTAA

KEYWORDS: coatings, engine, exhaust, high temperature, moisture, sealant

AF171-098

TITLE: Quantification of microtexture regions in titanium alloys using optical sensing methods

TECHNOLOGY AREA(S): Materials/Processes

OBJECTIVE: Develop optical-based experimental methods that can rapidly and cost-effectively characterize the size and the anisotropic crystal orientation of the alpha-phase for titanium alloys, for features 0.05 millimeters in scale and larger.

DESCRIPTION: While metallic forgings are often considered to be relatively homogeneous, they can contain significant variations in the internal microstructure that result from variability in upstream processing. Titanium alloys, for example, are prone to the development of “microtexture regions,” (MTR) wherein clusters of grains with similar crystallographic orientation persist over millimeter and larger length scales [1]. These microtexture regions can significantly impact the fatigue crack growth rate, especially under loading conditions containing tensile dwell periods.

One state-of-the-art method to accurately size and detect the presence of such features at the surface of metallic laboratory samples is Electron Backscatter Diffraction (EBSD) analysis using a Scanning Electron Microscope (SEM) [2]. While this method provides high spatial resolution data, it is a relatively slow process with typical data acquisition rates less than 1.5 kHz per data point, requires the sample to be placed within the SEM vacuum chamber with constraints over sample size and volume, and the sample surface must be nearly damage-free which can be laborious to prepare.

This solicitation is focused on the development of novel technologies that offer significant improvements relative to the state-of-the-art to rapidly detect and size both grains and MTR features in Titanium alloys. Of specific interest are optical-based experimental methods that are capable of quantifying the size and the anisotropic crystal orientation of the alpha-phase for titanium alloys, for features such as grains and MTR that are 0.05 millimeters in scale and larger, for sample areas in excess of 75 x 75 mm. It is critical that such techniques significantly reduce both the time and surface quality requirements compared to EBSD-based analysis. Other desired outcomes are that the characterization can be performed in air without the need for specialized environmental control, leveraging commercial-off-the-shelf technology if possible.

It is anticipated that rapid and accurate quantification of MTR in laboratory samples will allow for improved component design and lifting methodologies for systems that utilize titanium alloys, and, may also enable improvements in non-destructive inspection capabilities via correlative analysis and quantification of laboratory samples containing MTR. In addition, demonstration of the applicability of such technology to other aerospace or structural engineering alloy systems that contain phases with anisotropic optical properties, such as Titanium Aluminides, Beryillum, Magnesium, and Zirconium alloys is also desired.

PHASE I: Clearly define the system concept for the optical characterization system, which includes a detailed description of system capabilities, addressing both known and anticipated issues with system development and the technical approach to mitigate said issues, and estimates system cost.

PHASE II: Build a prototype using the design developed from Phase I. Demonstrate system performance on representative structural titanium alloys that contain selected grains and microtexture regions larger than 0.05 mm in scale, for sample areas in excess of 75 x 75 mm.

PHASE III DUAL USE APPLICATIONS: Grain and MTR quantification systems have the potential for use both at DoD facilities, as well as by original equipment manufacturers and the industrial materials supply base, which rely on microstructural characterization to fabricate, develop, and utilize alloys prone to MTR development.

REFERENCES:

1. N. Gey, P. Boucher, E. Uta, L. Germain, M. Humbert, “Texture and microtexture variations in a near-a titanium forged disk of bimodal microstructure,” Acta Materialia 60 (2012) 2647–2655.

2. Electron Backscatter Diffraction in Materials Science, Editors: Schwartz, A.J., Kumar, M., Adams, B.L., Field, D.P., (2009) Springer-Verlag,    DOI10.1007/978-0-387-88136-2.

KEYWORDS: characterization, microtexture, microtexture region (MTR), MTR, optical, optical characterization, titanium, titanium alloys

TECHNOLOGY AREA(S): Materials/Processes

OBJECTIVE: Develop sprayable paint system highly efficient (threshold 95% objective >98%) at reflecting or backscattering visible or shortwave infrared light for thermal control.

DESCRIPTION: Remotely piloted aircraft are deployed early and often to perform unusual or unique mission sets. Emerging operational needs may require sprayable coatings that achieve high visible (VIS) and short-wave infrared (SWIR) light rejection (i.e., via reflection or backscattering) to achieve precise thermal control. The objective of this topic is to develop specialty coatings for remotely piloted aircraft that are lightweight, serviceable, and highly efficient at reflecting/backscattering Vis/SWIR light. Relevant reviews of the scientific literature are given in the references section.