if i create an explotion with quick effect it the generated a trasparent material… why??
I’m not exactly sure what you mean, your post does not include any snapshots or detailed information, but this might help you http://cgcookie.com/blender/2011/12/02/tip-creating-quick-explosions/
The transparency is actually being controlled within the Quick Explode material’s texture. You’ll notice that it uses a “Blend” procedural texture with a color ramp to set the level of alpha throughout the animation, i.e. the object fades over time.
I think that the object’s material fades over time because in real life explosions can sometimes have heat and or fire, and this would lead to particles dissolving over time.
You can disable the “Fade” setting in the Quick Explode panel when you first initiate your Quick Explode effect.