I recall seeing silk in antique crazy quilts...it often is very frayed and wears out first...but it is pretty.
If you decided to do it I would suggest you back them with non woven interfacing...OK.. someone correct me on the interfacing name if I am wrong...it could be stabilizer or fusible...but it is NON WOVEN and fuses to the back of the fabric. It is what is used on T-shirt quilts...it keeps them from stretching out of shape.
If you do it...show us a picture!