#alloys

Self-Healing Ceramic Coating Seals Turbine Cracks at 800 °C

Inspired by natural glaze layers in cobalt superalloys, the new coating uses cobalt oxide migration to fill cracks, limit spallation, and protect extreme-environment engine components from heat-driven damage. In a recent research article available as an Article in Press in the journal Communications Materials, researchers developed a self-healing ceramic coating based on phase segregation in the CoO–Cr2O3 system that autonomously repairs thermally induced cracks at elevated temperatures, enhancing durability and lubricity for gas turbine engine applications. Extreme Environment Material Challenges Gas turbine engines experience extreme thermal and mechanical stresses, with surfaces exposed to temperature gradients that can reach 2000 °C, leading to material degradation through cracking and wear. Enhancing surface durability is essential for improving engine efficiency and meeting environmental targets.

back when we were learning to make clarinets in college in the 80s (a great throwaway phrase), we used nickel silver to forge clarinet keys by hand (which was very finicky but also satisfying), and we were told that technically the metal is a "nickel brass", since brass is fundamentally an alloy of copper and zinc

so we went to look up the alloy in wikipedia, and it casually lists off several alternative names for the alloy

Nickel silver

Shiny alloy of copper, nickel, and zinc

For the animal, see Alpaca.

Nickel silver, maillechort, German silver, argentan, new silver, nickel brass, albata, or alpacca is a cupronickel (copper with nickel) alloy with the addition of zinc.

and we were immediately jolted by the inclusion of alpacas to the discussion until we saw it mentioned in the list of alternative names for the alloy

so we went hunting for the reason why it's known as alpacca - and this is where it got really frustrating

though there's widespread mention of alpacca as being a name for the metal, no references we could find online had an explanation as to why it's called that - and the complete Oxford English Dictionary doesn't even reference it at all, which we admit shocked us to the core

the closest we've been able to get to it is a couple of references to it being a "trade name", but no searches so far have turned up who originally called it that

obviously we wondered (given the al- at the start) whether it's an arabic name, but so far we can't find any evidence of that either

and one other possibility is it's a bastardisation of albata, another name for the alloy - which in spite of also looking arabic is actually from the latin for "looks white" in reference to the surprising silveriness of a copper alloy

What is the difference between welding, brazing, and soldering?

A summary of the main points of difference between welding, brazing, and soldering are:

1. Temperature Range:

Welding: Above 1,200°C.

Brazing: From 450°C to 1,100°C.

Soldering: Below 450°C.

2. Strength of Joints:

Welding: Highest.

Brazing: Moderate.

Soldering: Lowest.

3. Applications:

Welding: Heavy-duty construction, automotive, aerospace.

Brazing: HVAC, electrical, automotive.

Soldering: Electronics, plumbing, jewelry.

4. Process complexity:

Welding: Requires high skill and complex equipment.

Brazing: Moderate skill and equipment.