Al-based plated steel plate

Abstract

A sheet includes: a base; an Al-plating layer on at least one of opposite surfaces of the base; an intermediate coating layer on a surface of the Al-plating layer; and a surface coating layer formed on a surface of the intermediate coating layer and containing ZnO particles with a mean particle size of 0.10 μm or more and 5.00 μm or less and an organic resin such that an amount of coating of the ZnO particles is 0.5 g/m2 or more and 10.0 g/m2 or less in terms of metallic zinc.

1 . An Al-plated steel sheet comprising:
 a base;   an Al-plating layer formed on at least one of opposite surfaces of the base;   an intermediate coating layer formed on a surface of the Al-plating layer; and   a surface coating layer formed on a surface of the intermediate coating layer, the surface coating layer comprising ZnO particles with a mean particle size in a range of 0.10 μm or more and 5.00 μm or less, and an organic resin such that an amount of coating of the ZnO particles is in a range of 0.5 g/m 2  or more and 10.0 g/m 2  or less in terms of metallic zinc, wherein the intermediate coating layer satisfies one of conditions (A) to (C) below:   
       (A) the intermediate coating layer has a thickness in a range of 10 nm or more and 1000 nm or less, and consists mainly of S, Al and O with a mass ratio [S]/[Al] of S to Al being in a range of 0.0008 or more and 0.49 or less, and a mass ratio [S]/[O] of S to O being in a range of 0.001 or more and 0.55 or less; 
       (B) the intermediate coating layer comprises an oxoacid salt comprising one of or two or more of borate, silicate, sulfonate, sulfinate, permanganate, and phosphate and has a deposition thickness in a range of 10 nm or more and 500 nm or less; and 
       (C) the intermediate coating layer comprises a fluorine salt of at least one of aluminum, alkali metal or alkaline earth metal such that a content of fluorine is 20 mg/m 2  or more. 
     
     
         2 . The Al-plated steel sheet according to  claim 1 , wherein
 the intermediate coating layer satisfies the conditions (A), and   the intermediate coating layer has a thickness in a range of 20 nm or more and 400 nm or less.   
     
     
         3 . The Al-plated steel sheet according to  claim 1 , wherein
 the intermediate coating layer satisfies the conditions (A),   the mass ratio [S]/[Al] of S to Al in the intermediate coating layer is in a range of 0.005 or more and 0.1 or less, and   the mass ratio [S]/[O] of S to O in the intermediate coating layer is in a range of 0.005 or more and 0.12 or less.   
     
     
         4 . The Al-plated steel sheet according to  claim 1 , wherein
 the mass ratio [S]/[Al] of S to Al in the intermediate coating layer is in a range of 0.008 or more and 0.05 or less, and   the mass ratio [S]/[O] of S to O in the intermediate coating layer is in a range of 0.01 or more and 0.08 or less.   
     
     
         5 . The Al-plated steel sheet according to  claim 1 , wherein
 the intermediate coating layer satisfies the conditions (B), and   the oxoacid salt is selected one of or two or more of sodium borate, sodium silicate, sodium phosphate, potassium phosphate, lithium phosphate, magnesium phosphate, calcium phosphate, aluminum phosphate, zinc sulfonate, sodium sulfinate, potassium permanganate, zinc orthosilicate, lithium silicate, and zinc permanganate.   
     
     
         6 . The Al-plated steel sheet according to  claim 1 , wherein
 the intermediate coating layer satisfies the conditions (B), and   the oxoacid salt is a mixture of permanganate and silicate, which are mixed at an Mn/Si mass ratio in a range of 1 or more and 50 or less.   
     
     
         7 . The Al-plated steel sheet according to  claim 1 , wherein
 the intermediate coating layer satisfies the conditions (C), and   the intermediate coating layer comprises fluorine in an amount of 2000 mg/m 2  or less.   
     
     
         8 . The Al-plated steel sheet according to  claim 1 , wherein
 the intermediate coating layer satisfies the conditions (C), and   the fluoride salt comprises at least one or two of AlF 3 , AlOF, LiF, NaF, KF, MgF 2 , and CaF 2 .   
     
     
         9 . The Al-plated steel sheet according to  claim 1 , wherein a three-layered structure comprising the Al-plating layer, the intermediate coating layer, and the surface coating layer is formed on each of the opposite surfaces of the base. 
     
     
         10 . The Al-plated steel sheet according to  claim 1 , wherein a content of Al in the Al-plating layer is, in mass %, 70% or more. 
     
     
         11 . The Al-plated steel sheet according to  claim 1 , wherein the base comprises:
 in mass %,   C: 0.01% or more and 0.5% or less;   Si: 2.0% or less;   Mn: 0.01% or more and 3.5% or less;   P: 0.1% or less;   S: 0.05% or less;   Al: 0.001% or more and 0.1% or less;   N: 0.01% or less; and   a balance consisting of Fe and inevitable impurities.   
     
     
         12 . The Al-plated steel sheet according to  claim 11 , wherein the base further comprises, in mass %, one of or two or more of:
 Ti: 0.005% or more and 0.1% or less;   B: 0.0003% or more and 0.01% or less;   Cr: 0.01% or more and 1.0% or less;   Ni: 0.01% or more and 5.0% or less;   Mo: 0.005% or more and 2.0% or less; and   Cu: 0.005% or more and 1.0% or less.   
     
     
         13 . The Al-plated steel sheet according to  claim 5 , wherein
 the intermediate coating layer satisfies the conditions (B), and   the oxoacid salt is a mixture of permanganate and silicate, which are mixed at an Mn/Si mass ratio in a range of 1 or more and 50 or less.   
     
     
         14 . The Al-plated steel sheet according to  claim 7 , wherein
 the intermediate coating layer satisfies the conditions (C), and   the fluoride salt comprises at least one or two of AlF 3 , AlOF, LiF, NaF, KF, MgF 2 , and CaF 2 .