Materials process chapter 2
What are functions of additional ingredients in silicon oxide solutions
1. Promoting fusion during heating 2. Increasing fluid he in molten glass 3. Retarding Divinci vacation (crystallizing in glass state) 4. Reducing thermal expansion 5. Improving chemical resistance 6. Adding color 7. Altering the index of refraction
Name the three groups of superalloys according to their base metal
1.Iron-based(Can be less than 50%) 2.Nickel based(Principally alloyed with chromium or cobalt) 3.Cobalt based(About 40 to 50% cobalt and 20 to 30% chromium) All of these are high-performance metals with high tensile strength, hot hardness, creep resistance, and corrosion resistance.
What temperature is delta phase
1394°C
Synthetic rubbers
3x tonnage of natural rubber Made of mostly petroleum Some rubbers: Butadiene (BR) Butyl (neoprene) Ethylene propylene Polyurethane Styrene-butadiene(40% of all rubber)
Composites
4th general category of materials. A material system composed of two or more physically distinct phases who's combination produces aggregate properties that are different from the ones the materials that make up the composites have.
What percentage of metal tonnage does steel and cast-iron take up
85%
What temperature is gamma phase
912°C This phase is important in designing heat treatment processes
What is a composite
A material system composed of two or more physically distinct phases who is combination produces aggregate properties that are different from those of its constituents. As in, We have combined the base materials, Metals ceramics and polymers, together to get a better material.
What is a cermet
A metallic matrix material with ceramic as the dominating phase in the mixture. An example is cemented carbides.
What is a polymer
A synthetic material (except for natural rubber) made of long chains of molecules. Most rubber products are made by a solidification process.
What are important applications of fiber reinforced plastics
Aerospace (Boeing 787) Automotive body panels Sports stuff (boat hulls, fishing rods, rackets, helmets, skis)
What are the three phases of iron
Alpha phase(Ferrite) Gamma phase (Austenite) Delta phase
What are some weaknesses of ceramics that might be corrected in fiber reinforced ceramic matrix composites
Although these have not been totally successful, ceramic matrix fiber composite try to correct: low toughness Low bulk tensile strength susceptibility to thermal cracking
What are abrasives typically made out of
Alumina and silicone carbide. Luminal is more used since it gives better results with grinding steel.
What is in feldspar
Aluminum silicate combined with either potassium, sodium, calcium, or barium
What is the solubility of carbon in steel
At the higher end of Alpha phase(723°C) it is 0.022% In gamma phase at 1130°C solubility is 2.1%
Why is austenitic stainless steel call by this name
Because it is in the austenite phase at room temperature. It also contains 18% chromium and 8% nickel. It has austenite structures from cryogenic temperatures to melting point temperatures.
What class of composite are cemented carbide
Because these are part of the cermets, cemented carbides are metallic matrix composites.
What is the chemical formula of ethylene the monomer for polyethylene PE (the most common plastic)
C2H4
Cemented carbide
Carbide compound bound in metallic matrix. Metallic binders are cobalt a nickel. Carbide ceramics constitute principal ingredient in cement to carbides. Tungsten carbide for cutting tools. Titanium carbide for high temp applications nozzle beans, bell seeds, thermocouple protection tubes, hard-working spinning tools.
What are applications of zinc
Casting(it has a low melting point) Galvanizing/coating Brass alloys Mass production automobiles and appliances Pennies
What are linear polymers
Chains of macromolecules produced by polymerization. This is the characteristic structure of thermal plastic polymer.
What is the most common alloy to create stainless steel
Chromium Chromium is typically greater than 15% of the alloy. This creates a thin impervious oxide film to resist corrosion. Another element would be nickel. We must have low carbon because it reacts with chrome to make chromium carbide which lowers corrosion resistance.
What is one of the most important applications of titanium nitride
Coating cutting tools. It has high hardness, good wear resistance and low coefficient of friction with ferrous metals. But unlike the other nitrides it is electrically conductive.
How do thermoplastic elastomers differ from conventional rubbers
Commonly used in footwear, rubber bands, and wire coating these are thermoplastics that behave like elastomers. They are not chemically cross-link but they have physical connections between soft and hard phases of incompatible substances that make up the material. Cannot be used in tires.
Cermet
Composite where ceramic is contained in metallic matrix. Finding enhanced through slight solubility at elevated temperatures. Important category is cemented carbide
What are the alloy elements for bronze
Copper and tin. Typically there is 10% tin.
What are the alloy elements for brass
Copper and zinc. Typically zinc is about 35% of the material.
What is the most important engineering property of copper that determines most of its applications
Copper has low electrical resistance and is abundant in nature so it is commonly used in electrical devices. It is also corrosion resistance (because it is a noble metal) and has high thermal conductivity
What are typical applications of cemented carbide WC-Co
Cutting tools, wire drawing dies, rock drilling bits and other mining tools, dies for powder metallurgy, and indenters for hardness tester's, and other applications where wear resistance and hardness are critical
How is cross-linking (curing or setting) accomplished
Depending on the starting ingredients the three ways are temperature activated systems(heat applied), catalyst activated systems(additive to liquid), or mixing activated systems(two main ingredients react to one another)
Fiber reinforced polymers
Embedded with fibers in matrix is usually thermoset like polyester or a epoxy sometimes thermoplastic polymers or elastomers are also used. Early for him made by stacking and binding in layers of fiber and polymers to desired thickness Applications: aerospace, military and commercial aircraft (fuselage, wings, tail, door, and interior), automotive body panels, boat hulls, tennis rackets, Golf club shafts, football helmets, Bows and arrows, skis, and bicycle wheels
What are the two major groups of metals
Ferrous metals And nonferrous metals The former contains iron(like steel and cast iron) and the latter does not... and that's the difference.
What are the common forms of the reinforcing phase in composite materials
Fibers, Flakes and particles Please take the load with the first phase deforms too far.
Where do we get silica
From quartz, and quartz is from Sandstone
Foam extender materials
Gas bubbles imbedded in polymer matrix. Styrofoam and polyurethane. Near zero density of gas plus low-density of matrix makes things extremely light weight. Guess also makes insulator for heat.
What is silica use for
Glass (A principal component) Whiteware Refractories Abrasives
What is most common as fibers in fiber reinforced plastics
Glass (in particular e-glass) Others are carbon, Kevlar, boron, silicone carbide, alumina and steel.
What distinguishes glass from new and traditional ceramics
Glass has a non-crystalline structure which causes it to be vitreous (clear and glassy). Silicon oxide is used widely because it naturally becomes glassy upon cooling from liquid. The term glass can also be a state of matter where the material is amorphous or noncrystalline.
) high strength Greater than 6.7%
Greater than 6.7%
What is the highest strength copper alloy
Heat treated beryllium - copper which is used for springs
Fiber reinforced metalmatrix composite
Hi tensile strength and modulus of elasticity in and low density so good strength to weight and stiffness to weight ratios. Typical metal: aluminum, magnesium, and 13 Fiber materials: boron, carbon, Al2O3, SiC
What are noteworthy properties of titanium
High strength to weight ratio Abundance Corrosion resistance High temperature strength (above 5500°C) Low thermal expansion
Important properties of fiber reinforced plastic composite materials
High strength to weight ratio High stiffness to weight ratio Low specific gravity
What are important properties of aluminum
High thermal and electrical conductivity Corrosion resistance Ductility/formabillity Low strength unless heat treated then it can compete with steel w/ high strength to weight ratio Abundant on earth Very affected by work hardening
Where is titanium carbide typically used
In high temperature applications
How are branched polymers formed
In polyethylene hydrogen atoms can be replaced by carbon atoms at random points initiating the growth of a branched chain at each location.
Fillers
Ingredients of secondary phase when used in polymer molding compounds. To categories: reinforcement, extenders Carbon black in rubber to increase strength and wear resist is ex of reinforcing category. Extenders increase bulk to reduce cost of polymers. Bubbles in foam are embedded in polymer matrix as extenders.
What are noteworthy properties of magnesium
Is the lightest of structural metals Catches fire easily at room temperature Soft and lax strength but can be alloyed/heat treated to get strength comparable to aluminum
What is a ceramic
It is an inorganic compound that is found in abundance in nature. These are hard and brittle and commonly used in glass or clay.
What is the most common base mineral for clay
Kaolinite(Al2Si2O5(OH)4)
Identify some of the common alloying elements other than carbon in low alloy steel
Manganese 13 Nickel 20 Molybdenum 40 Chromium 50-51 Vanadium (Cr-Vandium 61) (Numbers represent a AISI - SAE designation)
What are fiber reinforced metal matrix composites
Materials that combine high tensile strength and modulus of elasticity of fiber with metals of low density that achieving good strength to weight and stiffness to weight ratio's. Metals are typically aluminum, magnesium, and titanium. Fibers are aluminum oxide, boron, carbon, and silicon carbide
What are three basic categories of composite
Metal matrix composites Ceramic matrix composites Palmer matrix composites
What are some properties that distinguish metal from ceramic and polymer
Metals are: ductile malleable Have luster electrically conductive thermally conductive
What is an alloy
Meterials composed of two or more elements, where at least one of which is metallic. These types of metals enhance strength, hardness and other properties.
Thermosetting polymers
Molecules are a highly crossed linked structure rigid, brittle, less soluble, high service temps, not capable of remelting. The highest used thermosetting plastic is only 20% of highest used thermoplastic, polyethylene.
Natural (vulcanized) rubber
Mostly polyisoprene From latex which is milk from plants (rubber tree) Cured using sulfur and heat Hi string, tear resistance, resilience to wear and fatigue Largest market is tires
What is the molecular structure of thermosets
Network structure This is a highly cross-linked polymer that is essentially one gigantic macromolecule
Does silicone carbide (SiC) occur naturally
No, it is produced by heating mixtures of sand and Coke to temperature is around 2200°C
Ways to set a thermoset
One, temperature Two, CataList Three, mixing activated systems (ingredients are mixed and react)
What is the primary polymer ingredient in natural rubber
Polyisoprene A polymer of isoprene which is derived from latex found in many plants like the rubber tree. Rubber is extracted from latex by removing the water.
Elastomers(rubber)
Possible to have 500% extension 2 categories Natural rubber Synthetic rubber
Composite properties
Pros Superior to most other materials alone Hi strength to weight and stiffness to weight Better fatigue properties Hi toughness No I'm corroding Can have a combo of properties not attainable in metal, ceramic, or poly alone Cons Can be anisotropic (varying measurements from different directions) Subject to chemical attack Expensive, processing slow and costly
At what temperature is alpha phase
Room temperature
Polymer matrix composites
Secondary candy fibers, powder, or flakes. Most important of three classes. Types: Plastic molding compound, rubber reinforced with carbon black, and fiber reinforced polymers Properties: high strength to weight, stiffness to weight ratio's. Low specific gravity. Weight 1/5 of steel but close to strength in fiber direction
What are some ingredients of ceramics
Silica Alumina Hydrous aluminum silicate (Kaolinite)
What are the most important nitrides
Silicon nitride Boron nitride Titanium nitride
Besides high carbon content what other alloying element is integral in cast-iron
Silicone at about 3% makes iron suitable for casting.
What is the basic molecular structure of a polymer
Small molecules called monomers like ethylene are held together by covalent bonds. They join to form macromolecules which are very large molecules that chain together to form the polymer.
What are some important applications of nickel
Stainless steel Plating metal like plane carbon steel Good for corrosion resistance at high temperatures
What is the difference between traditional and new ceramics
The main difference between these is the way they are processed. The distinction is hard to make because aluminum oxide and silicone carbide are used in traditional and new ceramics. One tell of new ceramics is that they are usually chemically simpler than traditional ceramics
What is clay
The most widely used raw material in ceramics. It consists of fine particles of hydrous aluminum silicate that becomes a plastic substance that is formable when mixed with water. It is commonly based in mineral kaolinite
If elastomers and thermosets are both cross-linked why are they different
There is considerably less cross-linking in elastomers than in thermosets
What kind of polymer is nylon
Thermoplastic It is the most important member of the polyamide family which are strong, highly elastic, tough, abrasion resistant, and self lubricating.
What are the three categories of polymers
Thermoplastics Thermosetting palmers Elastomers
What is the difference between thermal plastic and thermoset
Thermosets are more rigid and brittle, less soluble in common solvents, capable of high service temperatures and they cannot be remelted after they are cold. Thermoplastics have low stiffness and strength, low hardness but high ductility and can be re-melted without any degradation of the material.
What are refractory ceramics
These are materials with high temperature resistance, thermal insulation and Glo chemical reactivity with the materials being melted in them. Typically alumina is used to form bricks for crucibles and furnaces to heat or melt materials.
What is the structure of thermoplastics
These are simply linear polymers(Without branches or cross-linking)
Identify characteristic properties of composite
These have superior properties than their ingredients by themselves: High strength to weight ratio, High stiffness to weight ratio (several times aluminum or steel) Better for fatigue properties High toughness Some do not corrode
How do properties of polymers compare to metals
They are cheaper than metals on a volumetric basis In volume, polymers generally require less energy to produce because working/forming temperatures are much lower for polymers
How do Fiber reinforced plastics compare to steel
They have 1/5 the weight yet strength and modulus are comparable in the fiber direction
What is the molecular structure of an elastomer
This is a lately cross-linked structure
What is anisotropic
This means we have different measurements of properties like strength or ductility from different angles of a material. For example looking parallel to fibers we have a much higher strength than perpendicular to fibers.
What are the three categories of ceramics
Traditional New ceramics Glasses
Where does alumina, an important raw material for traditional ceramics, come from
Typically bauxite but it can come from corundum which is a less common mineral that contains massive amounts of alumina
Ceramic matrix composites
Very difficult to make and not very successful. Consist of ceramic primary phase embedded with secondary phase, mostly fibers. Chemical compatibility with constituents in CMC's present difficulties. Ceramics used: alumina, for an carbide, boron nitride, silicone carbide, so good night tried, and titanium carbide and several glasses Fibers used: carbon, SiC, Al2O3
What is cross-linking
When a chain of macromolecules has branches sometimes primary bonding occurs between branches and other molecules which become cross-linked polymers. This happens because a portion of monomers are capable of bonding to adjacent monomers on more than two sides.
Where is feldspar used
When mixed with silica and clay it is used in stoneware, China, and other tableware.
How are superalloys hardened
With precipitation Particles that act to block the movement of dislocation and thus strengthen the metal