Bronze vs. brass — relative corrosion resistance In general engineering service, the corrosion resistance of bronzes is __________ compared with brasses.

Introduction / Context:
Brasses (Cu–Zn) and bronzes (traditionally Cu–Sn and related Cu–Sn–P alloys) are ubiquitous copper alloys. Choosing between them often hinges on corrosion resistance, strength, casting characteristics, and cost.

Given Data / Assumptions:

• Service includes atmospheric, fresh water, and marine environments.
• Typical compositions: brasses with significant zinc; bronzes with tin and sometimes phosphorus.

Concept / Approach:
Brasses can suffer selective leaching (dezincification) in certain waters, particularly hot, stagnant, or mildly acidic environments. Tin in bronzes enhances corrosion resistance, especially in seawater and many industrial fluids. Phosphor bronze also provides good fatigue and wear properties with robust corrosion performance. Therefore, as a general rule, bronzes are more corrosion resistant than brasses in many practical environments.

Step-by-Step Solution:
Identify key degradation mode in brass: dezincification and stress corrosion cracking in susceptible conditions.Recognise bronze advantages: tin-bearing bronzes resist many forms of aqueous attack.Conclude that bronzes are typically superior in corrosion resistance to brasses.

Verification / Alternative check:
Materials selection guides recommend bronzes for seawater valves/bearings, whereas brasses need dezincification-resistant grades or inhibitors for similar service.

Why Other Options Are Wrong:

• Inferior/about the same: contradict typical corrosion data in marine and aggressive waters.
• High only in dry air: bronzes also perform well in aqueous media.
• Unpredictable: while alloy details matter, the general trend is well established.

Common Pitfalls:
Assuming all copper alloys behave alike; zinc content makes brasses vulnerable in some environments compared with tin bronze.

Final Answer:
superior