[IngBell16]

Hi, I would like to know what happens when you mix phosphoric acid H₃PO₄ 80% and peroxyde H₂O₂ 30%, I've read that phophoric acid just dissociates in water, and phosphoric acid in mild concetrations behavi like a buffer. I've mixed both substance with a Ti plate to modified the
roughness of the surface, I've read that phosphirc acid is highly reactive with metals but reaction when a mixed them doesn't react agressive just afew bubbles and turns from transparant to yellow through time
I'll apreciate your help.

[Bond-IonicBond]

It sounds to me like you are just producing Ti(IV) phosphate over time.
Hydrogen peroxide is a strong oxidizing agent, but you have to remember that concentrated hydrogen peroxide is only 35% H2O2, meaning the rest is water. phosphoric acid will dissociate to H2PO4- (pH 3-4), H2O2 will oxidize Ti slowly (getting reduced to water) and Ti will be oxidized to Ti4+ that will react with phosphate to produce Ti(IV) phosphate.
If you want to check the reactivity of phosphoric acid with other metals the simplest thing would be to drop an iron nail into some and see what happens.

[Enthalpy]

Ti resists corrosion well, depending on the alloy, especially in oxidizing conditions, which is the case here. No wonder if it's not spectacular.