24-10-2012, 10:48 AM
Final Report on Initial Samples Supplied by LLNL for Task 3.3 Binder Burnout and Sintering Schedule Optimisation
ABSTRACT
Sixteen of the twenty-one samples have been investigated using the scanning laser dilatometer. This includes all three
types of samples with different preparation routes and organic content. Cracks were observed in all samples, even those only
heated to 300 C. It was concluded that the cracking was occurring in the early part of the heat treatment before the samples
reached 300 C. Increase in the rate of dilation of the samples occurred above 170 C which coincided with the decomposition
of the binder/wax additives as determined by differential thermal analysis. A comparison was made with SYNROC C material
(Powder Run 143), samples of which had been CIPed and green machined to a similar diameter and thickness as the 089 mm
SRTC pucks. These samples contained neither binder nor other organic processing aids and had been kept in the same
desiccator as the SRTC samples. The CIPed Synroc C samples sintered to high density with zero cracks. As the cracks made
up only a small contribution to the change in diameter of the sample compared to the sintering shrinkage, useful information
could still be gained from the runs. The sintering curves showed that there was much greater shrinkage of the Type III samples
containing only the 5% PEG binder compared to the Type I which contained polyolefin wax as processing aid.