composites-repairing technique

1) sand blasting with aluminium oxide particle. ( 30 micro meter ).

2) etching with HF acid .

3) application of silane coupling agent.
                                 
these techniques improves the bond strength while repairing composites,however depending on the type of the composites ,the above one of the methods can be used

                                                                                      REF:DM,2011,27,701-709