CAR Material Selection & Properties 3

Question 1

What is the significance of a material's Curie temperature in appliance recycling metal sorting?

Accepted Answer

Above this temperature, ferromagnetic metals lose their magnetic properties

Answer

It indicates the melting point of the metal

Answer

It determines the metal's scrap market value

Answer

It measures resistance to chemical corrosion

Question 2

Which refrigerant oil type requires separate collection because it is miscible with HFC refrigerants?

Accepted Answer

Polyolester (POE) oil

Answer

Mineral oil

Answer

Naphthenic oil

Answer

Paraffinic oil

Question 3

Acrylonitrile butadiene styrene (ABS) plastic in appliance housings is best identified by which characteristic?

Accepted Answer

It sinks in water and has resin code #7 or #9

Answer

It floats in water and has resin code #5

Answer

It has a greasy feel and resin code #4

Answer

It is transparent and has resin code #1

Question 4

Lead solder used in older appliance circuit boards is hazardous primarily due to its:

Accepted Answer

Toxicity and classification as a RCRA hazardous waste

Answer

High flammability when heated

Answer

Strong magnetic field interference

Answer

Corrosive reaction with plastic housings

Question 5

What property makes aluminum an energy-efficient choice for heat exchanger fins in air conditioners?

Accepted Answer

High thermal conductivity combined with low density

Answer

Low thermal conductivity compared to steel

Answer

High magnetic permeability for induction heating

Answer

High melting point for high-temperature applications

Question 6

In appliance recycling, 'zorba' refers to:

Accepted Answer

A mixture of shredded non-ferrous metals after steel removal

Answer

Pure aluminum recovered from compressors

Answer

The foam fraction separated from refrigerators

Answer

Copper wire stripped from motor windings

Question 7

Which material property determines whether a plastic component will sink or float during density-based separation in recycling?

Accepted Answer

Specific gravity relative to the separation medium

Answer

Tensile strength

Answer

Melting point

Answer

Color and opacity