You can try a product called J-B Weld. It is a 2 part product that
you mix like a two part epoxy. It is very thick, so I don’t know if
you will be able to use it in a syringe. However, on the back of the
package it states that it has a maximum temperature of 600 degrees.
You can find it in any hardware store for around $6.00.
Hope this helps.