Introduction
Tic-Ni3Al Cermets of Interest for Diesel Engine Applications

• High wear resistance and corrosion resistance
• Very good mechanical properties
  • High fracture strength, >100 Mpa
  • High fracture toughness, >12 Mpa (square root of m)
• Ability to match thermal expansion to steel (50 vol.% Ni3AI)
• Machine by electro discharge machining (EDM)
• Ni3Al has advantages in high temperature strength.

Approach and Objective

• Previous work on a lab-scale determined the processing-
  microstructure-property relationships.
• The objectives of the current effort are:
  • 1. Scale-up of the processing
  • 2. Manipulate microstructure to achieve better
    wear behavior
  • 3. Investigate cost-effective fabrication parameters

Results - Scale-up Processing

• Went from laboratory scale (<200 g/batch) to >3 kg/batch of milled powders
• Supplied >20 kg of blended powders to CoorsTek for forming into 'green' rods.
• Sintered 'green' rods to >98% T.D. and supplied the dense rods to Cummins
  Engine Co. for machining into components and subsequent engine testing

Results - Microstructure Manipulation for Improved Wear Behavoir

Normally faceted TiC grains can be "rounded" by the addition of minor alloying
additives which should improve wear behavior.

No Additives

Minor Alloy Additions

Results - Cost-effective Processing Methods

• Powder processing techniques similar to hardmetal industry and they are
  considered cost-effective
• Process economic analysis revealed that the NiAl precursor represented
  significant cost (~55% of raw material cost)
• Investigated different alternates to forming Ni3Al
  • Examined an inexpensive catalyst-grade Ni-Al alloy
    (~1/4 the cost of the typical NiAl powder)
  • Studied in-situ reaction to Ni and Al powder

 

Summary

• TiC-Ni3Al cermets have properties suitable for diesel engine applications
• Processing has been scaled-up from laboratory sizes to >10 kg batches
• Processing modified to obtain microstructures with good wear behavior
• Further development needed in employing cost-effective raw materials sources

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Research sponsored by the Heavy Vehicle Propulsion System Materials Program,
DOE Office of FreedomCAR and Vehicle Technology Program, under contract
DE-AC05-00OR22725 with UT-Battelle, LLC.