Module 6 - Materials and hardware

What is a ferrous material?

A material with a main component being iron

What’s are some properties of ferrous materials?

• commonly magnetic

• Atomic number is 26

• Density of 7.9 g/cm3

• Soft and ductile in pure form

How is steel created?

Steel = carbon + iron

How is cast iron made?

Cast iron is made by smelting it with limestone and coke (pure carbon form)

What is another name for cast iron, and what is it properties ?

Pig iron

It is very hard and brittle due to very high carbon content (3.7 - 4.8%)

Steel is created by ?

Usually created when remelting pig iron, and adding oxygen to reduce carbon content, then adding different alloying materials for desired properties

What is Strength?

Resistance to applied loads, e.g. tensile, compressive, shearing etc

What is Hardness?

Hardness is resistance to abrasion, penetrative forces things of that nature

What is malleability?

Malleability is the ability to mold and morph without fracture

What is ductility ?

Ductility is ability to pull metal into rods or wires without breaking

What is brittleness ?

Brittleness is the tendency to break on impacts without changing shape first

What is conductivity ?

Conductivity is the ability to carry heat or electricity

What is thermal expansion ?

Thermal expansion is the expanding or shrinking based on heat or cold

What is elasticity ?

The ability of the metal to return to original shape

What is toughness ?

Resistance to tearing when bent or stretched

What is fuse ability ?

The ability for a metal to join another, by melting

How does carbon affect alloy properties?

It increases hardness, strength, toughness - but in turn will increase brittleness

What is low carbon content classification ?

0.1 - 0.3% carbon content. For products like safety wire.

What is medium carbon content ?

0.3 - 0.5% carbon content. Products like machining or surface hardened parts

What is high carbon content ?

0.5 - 1.05% carbon content. Very hard parts, like files, springs, cutting tools.

What are 3 non corrosive stainless steel types (CRES)

Austenitic

Ferretic

Martensitic

What is austenitic CRES?

• 200 - 300 series

• Non magnetic

• Corrosion resistant

What is ferretic CRES?

• 400 series

• Magnetic

• Cost effective and weldable

What is martensitic CRES?

• 410, 420 series

• Magnetic

• Hardened by heat

• Some non corrosive properties

What is the SAE four digit alloy classification system?

Society of Automative Engineering

First 2 digits alloy elements

Last 2 digits is the carbon content

4130 - 41 chromium molybdenum 30 is 0.30% carbon content

What is heat treatment ?

Use of heating or cooling to change the mechanical properties of steel, without changing the shape or size.

What is quenching ?

Quenching is a heat treatment method where steel is heated and then rapidly cooled in water, air or oil. The rate of cooling dictates the hardness.

What is Annealing?

Annealing is the method of heating steel 10 degrees over the critical point, and then soaked at this temp. Makes it unsuitable for aviation due to being too soft.

What is Normalising ?

Normalising is the process of heating 38 degrees above the critical point, followed by the gradual cooling in air to reduce inner stresses and improve grain structure, commonly done after welding.

What is tempering?

Tempering is the process dome after Quenching, where thermocouple or pyrometer ovens to improve ductility and hardness. And reduce brittleness. The steel is held at these temps for a specific period and cooled slowly and specifically too for desired properties.

What is case/ surface hardening ?

This is where the outer surface is made harder, than the inner part of the steel. Beneifical for low alloy steel.

2 forms include carbonising (addition of carbon) or nitriding (addition of nitrogen)

What is carbonising and its effect?

diffusion of carbon into the surface level of steel creating a harder shell

What is nitriding and its effect?

introducing steel to a nitrogen rich environment, so it diffuses into the steels case to increase its strength, causes less distortion as is done at lower temps.

What is direct hardening?

Again where the surface us hardened though methods like flame hardening (flame followed by water jet) or induction hardening (heat coil surrounding whole surface which is then rapidly cooled)

What is a non ferrous material ?

Non - iron base, non magnetic

What ore does aluminium come from?

Bauxite ore

What is Cladding?

Cladding is the process of cold rolling a thin layer (3-5% of the thickness), of pure aluminium to prevent corrosion. Susceptible to puncture or scratches

Usually marked with A, Clad, ALC, al - clad.

What is 2024 ?

Copper + aluminium alloy

What is 7075 alloy?

Zinc + aluminium alloy

What is the ANSI?

American national standard institute

What is the most popular magnesium alloy?

AZ31, lightweight, strong, but can be corroded and flammable

What is the 4 digit code system in non-ferrous material ?

First digit is the main alloy being used

Second digit is the modification

The next 2 are to do with the alloy designator

What are some properties of titanium ?

Lightweight but very strong

Good under applied forces and heat

Corrosion resistant

What are 3 types of titanium

Alpha - good at high temps - weldable

Alpha beta - heat treatable, not weldable

Beta - very strong after heat treatment, good for forming

What are the 2 types of nickel alloy?

Monel - Monel is strong and corrosion resistant, made of 68% nickel and 29% copper

Inconel - inconel is temperature resistant, is 80% nickel, and 14% chromium

What are 3 main types of copper alloy in aviation?

Bronze

Brass

Beryllium

What alloys are 1 2 5 and 7 ?

1 - pure aluminium

2 - copper alloys

5 - magnesium alloys

7 - zinc alloys

What is solution heat treatment ?

Solution heat treatment is the process of heating the alloy to 460-525 degrees so all alloy metals dissolve in, its then quenched to be cooled rapidly, then salt bathed to remove impurities.

What is precipitation heat treatment ?

Also known as age treatment

Natural - Where the alloys are left to cool naturally in room temp

Artificial - where the alloys are reheated to 160-260 degrees

How many treatments can clad undergo?

3 until it starts to damage the corrosive resistant properties

What is strain hardening ?

Also known as cold handling, where the alloy undergoes rolling, drawing and pressing

What is T, T3, T4 and T6?

T - solution heat treated

T3 - solution heat treated + cold handling/strain hardening

T4 - solution treated + natural age hardening

T6 - solution treated + artificial age hardening

What is a composite material?

When 2 or more materials are combined to make a stronger one

What are the 2 materials making up a composite material ?

Matrix - the adhesive or resin layers

Reinforcement - the fabric or fibrous layer

What are some advantages of composite materials ?

• great strength to weight ratio

• Corrosion resistant

• Lightweight

• Long life span

• Can be easy to repair

What are some disadvantages of composite materials ?

• not much long term data

• Expensive and specialist equipment

• Use of hazardous materials

Advantages of fibre glass?

• cheap to use

• Non conductive

Advantages of Kevlar?

• strong tensile strength

• Lightweight

Advantages and disadvantages of carbon fibre?

• rigid, high compressive strength, but can be brittle

Advantages and disadvantages of Boron?

• strong and stiff, used in repairs but is hazardous and expensive

Advantages and disadvantages of ceramic?

• good heat resistance up to 1200 degrees, used in firewalls

What is warp?

Warp is the fibre direction moving with the direction that it pulls out at

What is weft?

Weft is perpendicular to warp,

What is the selvedge edge?

Selvage edge is the edge made to prevent fraying

What is fibre reinforcement ?

Use of running fibres through a matrix to carry a load or provide strength.

What is particle reinforcement ?

Use of spreading particles within matrix e.g. tungsten, or ceramic.

What is unidirectional style of fabric?

The running of fibres in one direction

What is bidirectional style of fabric?

Running fibres in 2 directions, warp and weft

What is quasi-isometric style of fabric ?

Where fibres are run in all directions, to ensure equal strength in all directions. (90, 45 -90, -45 degrees)

What is plain weave?

Plain weave is similar to bidirectional, where fibres run in 2 directions

Means that its simple, but has low degree of mechanic properties

What is twill weave?

Twill weave has better mechanical properties, it has better wet out properties

What is satin weave?

similar to twill weave but less intersections

Can be hard to handle

Has good wet out properties

Good mechanical properties

What does a resin matrix do?

It bonds together fibres, transferring the load between them

What are the 2 types of plastics? (Plus the 3rd one)

Thermoplastics

Thermosets

Epoxy resins

What is a thermoplastic?

Thermoplastics are able to be reheated and reset or re worked with

What is a thermoset?

Thermosets are only shapeable once, they can’t be reshaped after initial

What is a void?

Gaps were fibres aren’t glued together due to poor wet out

What are pre impregnated fabrics?

Where the resin comes already applied

What are some advantages and disadvantages of pre impregnated fabrics?

• perfect fabric to resin ratio

• Makes sure there aren’t any errors or voids

• But needs freezer storage and has short shelf life

• Expensive

What is the laminated method of composite production ?

Layers of matrix and reinforcement repeated and compressed and heated

What is the sandwich method of composite production ?

Where a core e.g. honeycomb or foam, is sandwiched between 2 face sheets

What are some advantages of plastic?

• lightweight

• Durable

• Corrosion resistant

• Easy to manafacture

2 types of clear plastic ?

Monolithic - single layer

Laminated - multiple clear epoxy bonded layers

What is PTFE?

PTFE or Teflon, great electrical insulator commonly used in wires

What is PEEK?

High temperature and everything else resistance, used in pump gears or valve seats

What is PCTFE?

Good temperature and chemical resistance so it can be used in exterior corrosive environments

What is PAI?

Temp resistance up to 260 degrees, used in thrust reverse components.

What are Seleants commonly used for in aviation?

To contain fluids, fuel, fires, pressure, preventing corrosion

What is a one part compared to a two part sealant?

One part - ready to use out the packaging

Two part - where the base and accelerant are required to be mixed before use

What is application time?

Application time refers to how long you have to apply the sealant before it hardens. B-2 = 2 hours

What is squeeze out life?

Squeeze out life refers to the time you have to join two faying surfaces, and get good squeeze out of air

What is tack free time?

Time taken for the seal to become no longer sticky to touch

What is cure time?

Time taken for the sealant to fully cure, influenced by temps and humidity

What is cure rate?

How long it takes/ how fast the sealant takes to cure

Over what temps do bubbling occur in sealets?

over 49 degrees bubbling occurs

What should be kept away from sealant ?

CO2, e.g. dry ice, as it will cause foaming

What type of fridge should sealant be kept in?

Mechanical fridge

What tool considerations need to be taken when using sealant ?

Separate tools to avoid contamination

What are some roles of adhesives ?

To bond structural components

Create streamlined surfaces

Saves weight by replacing fasteners

Protects electronics

What is Cyanoacrylate?

Fast setting super glues