Metal corrosion performance of triazole-containing compound preservatives and treated bamboo

ObjectiveTo provide a reference for selecting equipment materials and treated bamboo coatings, the corrosiveness and applicability of triazole-containing compound preservatives and treated bamboo for metal fasteners were investigated.

MethodReferring to the GB/T 34726—2017 and GB/T 34724—2017 standards, the metal corrosiveness of compound preservatives (active ingredient: propiconazole-tebuconazole (PPZ-TEB), iodopropynyl butylcarbamate (IPBC), isothiazolinone (CMIT-MIT)) and treated Moso bamboo (Phyllostachys edulis) was determined for Q235 carbon steel, 65Mn spring steel, 304 stainless steel, 201 stainless steel, H59 brass, T2 copper, 7075 aluminum alloy and 6061 aluminum alloy. The effect of coating on corrosion resistance was investigated by coating waterborne polyurethane varnish, waterborne acrylic varnish and wood wax oil on surfaces of bamboo-metal assemblies.

Result(1) After accelerated corrosion by soaking in compound preservatives, the corrosion rates of 304 stainless steel, 201 stainless steel, 6061 aluminum alloy and 7075 aluminum alloy were 0; the corrosion rates of Q235 carbon steel and 65Mn spring steel remained constant with time, and the discretization of them was larger in the early stage and gradually decreased in the later stage; the metal corrosion rates of H59 brass and T2 copper soaking in A, C, CK₁ and CK₂ and contacting treated bamboo were 0, and both metals soaking in B had slight corrosion. (2) After accelerated corrosion by contacting treated bamboo, the corrosion rates of 304 stainless steel, 201 stainless steel, H59 brass and T2 copper were 0; the corrosion rates of Q235 carbon steel and 65Mn spring steel decreased with time and tended to be flat, and the corrosion degree was significantly greater than that of compound preservatives; 6061 aluminum alloy and 7075 aluminum alloy had slight corrosion. (3) The corrosiveness of compound preservatives and treated bamboo for Q235 carbon steel and 65Mn spring steel was respectively: CMIT-MIT (CK₁) > PPZ-TEB/CMIT-MIT (C) > PPZ-TEB/IPBC (B) > PPZ-TEB (A) > Untreated (CK₂) and C > CK₁ > B > A > CK₂. (4) After coating the surfaces of bamboo-metal assemblies of Q235 carbon steel and 65Mn spring steel with waterborne polyurethane varnish, waterborne acrylic varnish and wood wax oil, the corrosion rates of treated bamboo showed reduction. Wood wax oil had better corrosion resistance than waterborne polyurethane varnish and waterborne acrylic varnish.

ConclusionThe triazole-containing compound preservatives and treated bamboo are not corrosive to 304 stainless steel and 201 stainless steel. The compound preservatives and treated bamboo are almostly not corrosive to H59 brass and T2 copper. The corrosion rates of compound preservatives for Q235 carbon steel and 65Mn spring steel remain constant with time, while the corrosion rates of treated bamboo decrease with time and tend to be flat. And the former is smaller than the latter. The compound preservatives have no corrosion for 7075 aluminum alloy and 6061 aluminum alloy, and treated bamboo has slight corrosion. The corrosiveness performance of compound preservatives and treated bamboo for Q235 carbon steel and 65Mn spring steel is: C > B > A. The corrosiveness performance of treated bamboo can be reduced by coating.