Metalworking Fluid Delivery Using Supercritical CO2: An Environmentally Preferable Alternative to Aqueous SystemsEPA Grant Number: FP916414
Title: Metalworking Fluid Delivery Using Supercritical CO2: An Environmentally Preferable Alternative to Aqueous Systems
Investigators: Clarens, Andres F.
Institution: University of Michigan
EPA Project Officer: Lee, Sonja
Project Period: January 1, 2004 through December 31, 2006
Project Amount: $109,744
RFA: STAR Graduate Fellowships (2004) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Fellowship - Environmental Engineering , Engineering and Environmental Chemistry
The objective of this research project is to develop alternative delivery mechanisms for industrial lubricants used in metal cutting to improve upon both the performance of traditional water-based fluids and to reduce the environmental impacts of these traditional fluids. Metalworking fluids (MWFs) serve to lubricate and cool the interface between a work-piece and a tool, while removing chips during metal cutting processes. They generally consist of oil in water emulsions with the oil providing the lubrication and the water providing the cooling. This mixture of oil and water makes the MWFs an environmental and occupational health problem because microorganisms thrive in the fluids; the MWFs require a number of additives including biocides, corrosion inhibitors, and anti-foaming agents, resulting in a hazardous waste problem when they reach the end of their useable life. An obvious development to MWF technology would be to investigate alternative solvents, particularly given that alternative eco-friendly solvents have proven successful in other industrial processes. One such solvent is supercritical carbon dioxide (scCO2). scCO2 is produced by raising CO2 above its critical temperature and pressure where it takes on unique solvency properties. scCO2 has been used successfully in a number of other industrial applications including metal cleaning and coating.
This research project will investigate oil in scCO2 emulsions and assess their performance in metal cutting applications relative to traditional oil in water emulsions. A few of the oils that will be investigated are soy, canola, and mineral oils. In addition, it is possible that surfactants (surface active agents that permit two immiscible phases to mix) will be necessary to achieve stable oil in scCO2 emulsions. An analysis will be conducted on the additives (e.g., extreme pressure) that are required in most metal cutting processes to determine how they would behave in a scCO2 system. The fluids formulations will be tested for performance using a tapping torque machine as well as wear scar analysis. Life-cycle analysis will be used to interpret the implications of switching to nonaqueous-based fluids. Finally, an economic and regulatory analysis will be conducted to understand the hurdles and challenges associated with the proliferation of the new technology.