| Compare list |
hot blast galvanized |
hot dip galvanized |
| procedure |
high voltage electric-arc equipment,will melt the Zinc-wire to liquid-zinc,high pressue blast the liquid-zinc to zinc-fog to the surface of the steel-product.(the steel-product have been sand-blasted at first,so the zinc have a good combination with the steel) |
A big pool,pool be heated to 550~600℃,zinc is melted in the pool.Put steel-product in the pool.(the steel should be acid-washing at first) |
| thickness of Zinc-layer |
Zinc layer thickness can be controled as requirement,thickness is 50-250μm available,and thickness of the zinc-layer is uniform |
thickness of the layer is 50-80μm,and if the surface of the steel-product is not smooth,the zinc-layer would not uniform |
| requirement about the size of the steel-product |
big size and small size are also ok,even very big size steel-product,it's also OK. |
depend on the size of the zinc-pool,if zinc-pool is small,big size steel-product is can't be operated |
| melted-zinc's high temprature lead to thermal-stress |
the heat loss quickly,and the surface of the steel-product won't over 250 ℃,won't lead to stress deformation. |
The total steel-product will in the zinc pool all the way,and the 550~600℃ temparature will lead to big stress deformation |
| pre-treatment method |
sand blasting treatment.
After sand blasting,the surface of the steel product is rough,and can have a good combination with the zinc layer |
Acid washing treament |
| the combination-strength between the zinc-layer and the surface of the steel-product |
over 20MPa. |
lower than 10MPa.and if the thickness of the zinc-layer is over 70 μm,easy to separate the zinc-layer out of the steel-surface. |
| repairing about the zinc-layer |
if zinc-layer is damaged in transporting,welding,etc.easy to blast and repairing it again |
if zinc-layer is damaged in transporting,welding,etc.can't use hot-dip to repair it,only can use hot-blast-zinc to repair it. |
| operating place |
can be operated in any time,any place. |
only can be operated in zinc pool |
| environmental protection |
New tecnology,use equipment to operate,won't polute the environment,material is Zinc-wire,can begain and stop any time.
Sand blasting is also very low polution for air. |
Very old method for anti-rust,the zinc-pool need to keep heating all the way,and waste lot of zinc-material.
Acid washing is high polution for the water. |
| disadvatage |
the blast gun can not go in to small hole of the steel-product |
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