The objective of this award is to develop a collagen-based binder that can be used in foundry core sands. Cores create the hollow cavities within cast iron products; and the cores are comprised of silica sand plus a core binder. The aim is to replace petroleum-based binders that use phenolic urethane or furan / toluene. The collagen offers a means of creating a sustainable binder from a US food processing source that is otherwise mostly discarded. The collagen binder will release about 20-30% as much volatile organic compounds into the air, when compared to the conventional petroleum-based binders. The work herein will focus on discerning a favorable cross-linker that will cause one collagen strand to chemically bind to neighboring strands. This will increase the strength of the binder, and render it less susceptible to softening when immersed in water, as when applying a core wash. Preliminary results show that a cross-linker will yield a binder that hosts a tensile strength of 300-400 pounds per square inch, when 1% collagen-based binder is used.
This transformative research aims to provide a means for foundries to diminish pollution while delivering high-quality iron castings. This will help the foundries be good neighbors in the local communities, while maintaining important manufacturing jobs in America. The research will open the way for collagen to be used in a broad range of new applications that include medicine, environmental sorbents, and electronics. This research and development will engage a Ph.D. candidate who has worked in the foundry industry. In this role, this student devised a means to cut foundry sand waste, via other NSF-funded projects. As a deliverable, the results will be widely disseminated via refereed journal papers and conference presentations. Also, with foundry partners, the subsequent aim is to test these collagen-based binders at the demonstration-scale or full-scale.
This project is jointly funded by the Materials Processing & Manufacturing Program, of the Civil, Mechanical, and Manufacturing Innovation Division and by the Grant Opportunities for Academic Liaison with Industry Program of the Industrial Innovation and Partnerships Division.
Award ID: #0906271 and #1049103 Principal Investigator: Cannon, Fred S. Organization: PA St U, University Park In this SGER grant that was amended with a TRAC grant, the Penn State team has been devising collagen-alkali silicate binder systems for cores that do not cause much volatile pollution for phenolic urethane binders that do release volatile pollution extensively. In a foundry setting, binders hold together sand grains in the shape of the "cavity" that molten iron will pour around. Then when the iron solidifies, the core holds the iron in the desired shape. Binders should hold these sand grains together when exposed to 1500C molten iron; and then after the iron solidifies, the binders should fall-apart so that the sand grains can be used again. Phenolic urethane has been used for many decades; and it can achieve this needed result. However, the phenolic urethane binders also cause extensive volatile organic carbon (VOC) pollution. The objective of the SGER grant was to devise a alkali silicate-collagen binder system that achieved the same thermal stability and shake-out properties, but without causing as much pollution. The first task was to devise laboratory and pilot-scale protocols that could usefully simulate full-scale foundry operations. Many of these laboratory analytical protocols had not previously been developed for simulating foundry operations relative to core binders. Thus, a significant portion of our initial SGER activity was devoted to devising such laboratory protocols. Starting from ground zero, we sought to use themogravimetry to rapidly appraise core binder formulations. This, various chemical cross-linkers were coupled with collagen so as to improve the resistance to thermal decomposition. Thermogravimetry confirmed that cross-linkers used herein could improve the thermal stability of collagen. However, the collagen and sodium silicate composite proved to produce the most favorable thermogravimetric response, as this response most closely resembled the phenolic urethane response. Beyond thermogravimetry, hot distortion tests were utilized to further rapidly assess core behavior at high temperatures. Hot distortion tests further elucidate how a binder will perform at full-scale. Another portion of this activity was to discern whether organic cross-linkers could enhance this binder strength under the intense thermal conditions; and the research discerned that aldehydes and alcohols could enhance the thermal recalcitrance. As the TRAC amendment to this SGER, the Penn State team has been making bindered cores in a Harrison Machine Company Core Making Machine, which has recently been set-up in the Penn State Pilot Foundry. The market opportunity of these novel low-pollution binders has been characterized as quite favorable. The Penn State team is making cores that host acceptable scratch hardness and considerable unconfined compressive strength. The team successfully completed a second round of demonstrations of these cores in a full-scale partnering foundry, HMAC, Lawrenceville, PA. For this, the Penn State team made cores with the collagen-alkali silicate binder system in the Penn State core making machine, provided by Harrison Machine Company. With 244 of these cores used in full-scale production of damper forks, none of the castings were defective in the core area. The appraisal was conducted by the foundry's QA personnel who were "blind" to the nature of the trial, and who used the same QA ratings as for their conventionally-made castings.
