Applied Dental Materials 2 Lecture 1 (Soldering)

Front 1

In soldering and brazing, metal parts are joined using a filler material, (with/without) the use of pressure

Back 1

without

Front 2

Parts to be joined are heated to temperature (above/below) the solidus temperature of substrate

Back 2

below

Front 3

True or false, in soldering, the metals are alloyed and diffused

Back 3

False!

Front 4

True or false, in soldering, there is no change in dimensions of the joined structure

Back 4

True

Front 5

The (substrate/filler) metal needs to have a LOWER melting point than the other

Back 5

filler

Front 6

What is the term for a physically distinct, homogeneous, mechanically separable portion of a system with a unique crystal structure and unique physical properties.

Back 6

metallurgic phase

Front 7

What is the main difference between soldering a brazing? (hint: temperature)

Back 7

soldering, filler has liquidus temperature lower than 450

brazing, filler has a liquidus temperature higher than 450

Front 8

in dental procedures, we use (soldering/brazing). Why is this a misnomer?

Back 8

brazing... BUT, it's often called soldering even though temperatures do excede 450, technically called brazing

Front 9

What is the purpose of soldering flux?

Back 9

to prevent formaiton of, and to remove, oxide layer on metal surface

Front 10

What helps remove and prevent oxide layer and metal surface?

Back 10

flux

Front 11

True or false, flux should wet the substrate

Back 11

True

Front 12

Which type of flux prevents O2 access?

Back 12

Type 1

Front 13

Which type of flux reduces oxides and exposes clean metal?

Back 13

Type 2

Front 14

Which type of flux dissolves oxides and corrosion products, and carries them away?

Back 14

Type 3

Front 15

True or False, all fluxes work by preventing O2 access

Back 15

False! Only type 1 prevents O2 access, type 2 and 3 work via a different mechanism

Front 16

Fluxes for (N/HN/PB) alloys act as type 1 and 2 fluxes, used with Gold solders

Back 16

N (noble)

Front 17

fluxes with borax, boric acid, and boric anhydride work on (N/HN/PB) alloys

Back 17

N (noble)

Front 18

PB (predominantly base metal) alloys, use ____ based fluxes

Back 18

fluoride

Front 19

Fluoride fluxes are used with (gold/silver) and borax fluxes are used with (gold/silver)

Back 19

silver; gold

Front 20

fluoride fluxes act as type (1/2/3)

Back 20

3

Front 21

Borax fluxes act as type (1/2/3) (choose two numbers)

Back 21

1 and 2

Front 22

What is the term for the substance in a tube containing both solder and the flux

Back 22

prefluxed solder

Front 23

what is the goal of an anti-flux?

Back 23

to prevent solder from flowing into undesirable places

Front 24

what are two common anti-fluxes (as discussed in lecture)?

Back 24

graphite; rouge in chloroform

Front 25

The ideal solder:

(should/should not) wet the substrate metal

(good/poor) color

(resistant/susceptible) to tarnish and corrosion

Back 25

should, good, resistant

Front 26

The ideal solder:

flow temperature should be at least ___ degrees C BELOW solidus temperature

Back 26

55.6

Front 27

Dental solders are considered (soft/hard)

Back 27

hard

Front 28

What is the melting point range of a soft solder?

Back 28

250-300 C

Front 29

What is the melting point range of hard solders?

Back 29

> 450 C

Front 30

(soft/hard) solders are also known as "plumber's solder"

Back 30

soft

Front 31

Which has better mechanical properties and corrosion resistance, hard or soft solder?

Back 31

hard

Front 32

Ortho solders are typically (gold/silver)

Back 32

silver

Front 33

What are the 5 main alloys in gold solders?

Back 33

Au, Ag, Cu, Sn, Zn
gold, silver, copper, tin, zinc

Front 34

What component of gold solders is NOT in casting alloys?

Back 34

tin

Front 35

What two metals are in casting alloys but NOT gold solder?

Back 35

Pd, Pt
Palladium, platinum

Front 36

What are two main uses of gold solder?

Back 36

crowns, bridges

Front 37

The "fineness" of gold solders is determined by the content of what metal?

Back 37

gold

Front 38

What are the three main metals used to in the solder for orthodontic appliances?

Back 38

Ag, Cu, Zn
Silver, copper, zinc

Front 39

Silver-copper eutectics usually have a (lower/higher) melting point than other silver solders

Back 39

lower

Front 40

What did Dr. Khajotia say was the most important aspect of solders, behind "wetability"

Back 40

flow temperature

Front 41

The higher the fineness of a solder, the (higher/lower) the liquidus temperature

Back 41

higher

Front 42

Solder flow temperature should be (below/above) substrate solidus temperature by at least ___ C

Back 42

below, 55.6

Front 43

What are the three main consequences of having a solder temperature that is too close to substrate temperature?

Back 43

melting or sag of substrate

recrystallization (change in grain size)

damage to porcelain

Front 44

(Gold/Silver) solder has a higher liquidus temperature

Back 44

gold

Front 45

High fineness = (high/low) tensile strength, flow, corrosion, and brittleness

Back 45

low

Front 46

The bond between solder and substrate is (mechanical/chemical)

Back 46

mechanical

Front 47

Bond between substrate and soler only happens in the (presence/absence) os surface oxides

Back 47

absence

Front 48

The oxidizing zone of a flame is the (inner/outer)most portion

Back 48

outer

Front 49

The reducing zone of a flame is just below what zone?

Back 49

oxidizing zone

Front 50

What are the zones of a flame, from outside to inside?

Back 50

oxidizing zone, reducing zone, partial combustion zone, cold mixing zone

Front 51

Which of these is the least common solder heating method?

flame, oven, infrared

Back 51

infrared

Front 52

solder is drawn (towards/away from) heat in the reducing zone

Back 52

towards

Front 53

Rank these from LOWEST to HIGHEST heat content

Hydrogen, acetylene, propane, natural gas

Back 53

H, NG, Acet, Prop

Front 54

Which zone eliminates oxides?

Back 54

reducing

Front 55

Overheating causes which of the following?

a. change in metal substrate
b. lack of solder flow
c. poor wetting of substrate
d. alloying of solder and substrate

Back 55

a and d only

Front 56

Underheating causes which of the following?

a. pitting of solder joint: boil SN or Zn
b. distortion or meltdown of substrate
c. pitting of solder joint: flux inclusions

Back 56

c only

Front 57

What is the ideal gap size?

Back 57

0.1-0.3 mm

Front 58

What happens of the solder joint is too large?

Back 58

mechanical weakness, can't fill joint

Front 59

What happens of the solder joint is too small?

Back 59

incomplete joint

Front 60

What is the term for the process of brazing or soldering two or more metal components of a prosthesis after the metal substructure has been veneered with a ceramic?

Back 60

postsoldering

Front 61

What is the term for the process of brazing or soldering two or more metal components of a prosthesis before a ceramic veneer is fired or hot-pressed on the structure?

Back 61

presoldering

Front 62

What procedure is often used in place of presoldering to avoid uncertainties and variations?

Back 62

cast-joining

Front 63

What is the most likely cause of failure when using presoldering of parts?

Back 63

overheating

Front 64

Base metal alloys tend (to form/to not form) stable oxides

Back 64

to form

Front 65

Why is it bad if a lab presolders a base-metal alloy?

Back 65

bc flux cannot often remove all of those oxides

Front 66

Cast-joining is preferred in (N/HN/PB) alloys, especially those of Nickel-chromium

Back 66

PB

Front 67

True or false, cast-joining allows you to put a bride together by inserting it in two pieces, even if they have different paths of insertion

Back 67

True

Front 68

A cast-joined area is held by (chemical/mechanical) retention

Back 68

mechanical

Front 69

True or false, welding is done under pressure

Back 69

true

Front 70

In terms of the outcome of metal, what is the big difference between welding and soldering?

Back 70

in welding, the metals ARE alloyed together

Front 71

True or False, welding creates a chemical bond

Back 71

true