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Brass water heating dead block water glass investment casting parts

H70 Brass Material Name: H70 Brass (Hard ≥ 0.5mm) Grade: H70 C2600 Standard: National Standard GB/T 5231-2001 Japanese Standard JIS H3100:2006 American Standard ASTM B36/B36M: 2008

In a 10% H 2SO4 medium, the corrosion potentials E cor of Ta coating and TaC/Ta composite coating were -0.428V and -0.39V, respectively, which were 0.112V and 0.15 V higher than the C17200 substrate (-0.540V). The corrosion current densities I cor were 1.17 × 10-6 A/cm2 and 2.64 × 10-7 A/cm2, respectively, which were reduced by about two to three orders of magnitude compared to the substrate (1.73 × 10-4 A/cm2), indicating a smaller corrosion tendency and rate. The electrode impedance value of Ta coating and TaC/Ta composite coating is higher than that of the substrate, resulting in greater charge transfer resistance, slow electrode process, and reduced corrosion rate. The outer layer of the corrosion surface of C17200 substrate is loose, and the grain boundaries undergo corrosion. The corrosion product is copper oxide. The surface corrosion morphology of Ta coating and TaC/Ta composite coating shows little change compared to the uncorroded surface, with no corrosion products or pitting phenomenon. The surface is a dense Ta2O5 thin film, which has improved corrosion resistance compared to the substrate. H70 brass has excellent plasticity and high strength, good cutting performance, easy welding, and is not resistant to general corrosion, but prone to cracking. Used for complex cold drawn and deep drawn parts, such as radiator casings, conduits, corrugated pipes, casings, and gaskets.

In a 20% H2SO4 medium, the corrosion potentials E cor of Ta coating and TaC/Ta coating were -0.39 V and -0.40 V, respectively, which were positively shifted by 0.41 V and 0.42 V compared to the C17200 substrate. The corrosion current densities I cor were 8.23 × 10-5 A/cm2 and 7.62 × 10-5 A/cm2, respectively, which were reduced by about an order of magnitude compared to the substrate (2.5 × 10-4 A/cm2). Ta coatings and TaC/Ta composite coatings exhibit greater impedance than the substrate, slowing down the electrochemical corrosion process. The surface corrosion of C17200 substrate is severe, with obvious precipitation of corrosion products such as copper oxide. There is a small amount of pitting corrosion on the Ta coating and TaC/Ta coating corrosion surfaces. The coating surface is a layer of Ta2O5 film to protect the interior of the coating from corrosion by H2SO4 solution. Chemical composition: Copper Cu: 68.5~71.5 Zinc Zn: Residual lead Pb: ≤ 0.03 Nickel Ni: ≤ 0.5 Iron Fe: ≤ 0.10 Beryllium Sb: ≤ 0.002 Bismuth Bi: ≤ 0.002 Note: ≤ 0.3 (impurity) Ta coating and TaC/Ta composite coating have more severe corrosion in 20% H 2SO4 medium than in 10% H 2SO4 medium, and the passivation phenomenon is more obvious. The passivation film is thickened, and the Ta coating and TaC/Ta composite coating do not peel off as the concentration of the corrosive medium increases. A stable and dense Ta2O5 thin film is formed on the surface, improving the corrosion resistance of beryllium copper substrate.

Mechanical properties Tensile strength σ b (MPa): ≥ 390 Elongation rate δ 10 (%): ≥ 12 Note: Tensile mechanical properties of sheet metal Sample size: Thickness ≥ 0.5

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