A two-component aqueous coating composition comprising: A an aqueous resin component comprising a carboxyl-functional resin; and B a substantially water-free hardener component comprising: - a carbodiimide comprising in the range of from 1 to 20 carbodiimide moieties and terminal and/or pendant non-ionic emulsifying groups; and - an alkoxylsilane selected from the group consisting of an alkoxysilane of general formula R 1 [-(CH 2) n -Si(OR 2) 3-m (R 3) m] p and a tetraalkylorthosilicate of general formula Si(OR 2) 4 wherein: m is 0 or 1; n is an integer with a value in the range of from 0 to 6; p is 1 or 2, preferably 1; R 1 is an organic group comprising an epoxide group, a vinyl group, or a (meth)acryloyl group, or is a hydrogen atom and R 1 does not comprise a carboxylic functional group, a mercapto-functional group, or an amine-functional group; R 2 is an alkyl group having 1 to 4 carbon atoms; and R 3 is an alkyl group having 1 to 4 carbon atoms, wherein the weight ratio of the carbodiimide to the alkoxysilane in hardener component B is in the range of from 10:90 to 85:15. A an aqueous resin component comprising a carboxyl-functional resin; and B a substantially water-free hardener component comprising: - a carbodiimide comprising in the range of from 1 to 20 carbodiimide moieties and terminal and/or pendant non-ionic emulsifying groups; and - an alkoxylsilane selected from the group consisting of an alkoxysilane of general formula R 1 [-(CH 2) n -Si(OR 2) 3-m (R 3) m] p and a tetraalkylorthosilicate of general formula Si(OR 2) 4 wherein: m is 0 or 1; n is an integer with a value in the range of from 0 to 6; p is 1 or 2, preferably 1; R 1 is an organic group comprising an epoxide group, a vinyl group, or a (meth)acryloyl group, or is a hydrogen atom and R 1 does not comprise a carboxylic functional group, a mercapto-functional group, or an amine-functional group; R 2 is an alkyl group having 1 to 4 carbon atoms; and R 3 is an alkyl group having 1 to 4 carbon atoms, wherein the weight ratio of the carbodiimide to the alkoxysilane in hardener component B is in the range of from 10:90 to 85:15. - a carbodiimide comprising in the range of from 1 to 20 carbodiimide moieties and terminal and/or pendant non-ionic emulsifying groups; and - an alkoxylsilane selected from the group consisting of an alkoxysilane of general formula R 1 [-(CH 2) n -Si(OR 2) 3-m (R 3) m] p and a tetraalkylorthosilicate of general formula Si(OR 2) 4 wherein: m is 0 or 1; n is an integer with a value in the range of from 0 to 6; p is 1 or 2, preferably 1; R 1 is an organic group comprising an epoxide group, a vinyl group, or a (meth)acryloyl group, or is a hydrogen atom and R 1 does not comprise a carboxylic functional group, a mercapto-functional group, or an amine-functional group; R 2 is an alkyl group having 1 to 4 carbon atoms; and R 3 is an alkyl group having 1 to 4 carbon atoms, m is 0 or 1; n is an integer with a value in the range of from 0 to 6; p is 1 or 2, preferably 1; R 1 is an organic group comprising an epoxide group, a vinyl group, or a (meth)acryloyl group, or is a hydrogen atom and R 1 does not comprise a carboxylic functional group, a mercapto-functional group, or an amine-functional group; R 2 is an alkyl group having 1 to 4 carbon atoms; and R 3 is an alkyl group having 1 to 4 carbon atoms,