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14 Cards in this Set
- Front
- Back
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Soldering لحام -Def -Name of Phenomena -MCQ difference between brazing and soldering |
-Joining of 2 parts of Eutectic Alloy using a 3rd Alloy called solder -Adhesion -brazing req heating temp above 450 C |
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Req : A) MCQ melting temp should be Compared to parts to be soldered B) Strength C) If subjected to Overheating it shows D) Easy Flow related to E) Free Flow related to w so providing F) MCQ thickness of joint Must be w GR |
A) 100 C less than it B) High C) No Pitting or volatilization D) Low fusing temp E) Low Surface Tension... Good wetting w Adhesion F) not exceed 0.005 inch... Bec increase in thickness leads to increased possibility of failure |
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Types of Solders |
Soft Hard |
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1)Soft -used or not in dentistry -involves use of -GR are impractical for dental apps 2)Hard -melting temp Compared to Soft -Types app in dentistry |
1) -not - PbSn Eutectic Alloy -Bec they lack Corrosion resistance 2) -higher -Gold w Silver solders |
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Gold -MCQ For soldering A) Comp : If white color is needed so what used B) MCQ Designation of solder : -when we say 14 karat solder this means w not indicate -Gold content Must be kam to give good Corrosion resistance -fineness or karat of solder should be more or less Compared to karat or fineness of parts being joined C) Prop -Corrosion Resistance -Relation between hardness w fineness of. Solder -%Elongation high or low w so give solder Brittle or Ductile than alloys to be soldered -NB GR For Investment, solder will have higher hardness w Strength w lower ductility |
-gold alloys A)Ni replaces Cu B) - This solder used for soldering 14K gold... Its Gold content -not less than 60% -slightly less than C) -good -Indirect -low... Brittle -Due to hardening heat treatment during soldering operation |
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Ag Solder -used when what is desirable -in case of -Prop : Increased Thickness may lead to |
-low fusing solder -Base Metal alloys w St Steel -Fracture |
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MCQ Flux = Flow الحاجات اللي بيضفها المصنع جوا الsolder -its Melting temp Compared to solder Alloy A) Comp : -in case of gold -in case of St Steel and Co-Cr w GR B) Eff |
-Less than by 80 C A) -Boric Acid flux -F Flux... Bec Borax w Boric Acid alone are not Sufficient to Remove Surface Cr oxide layer B) -Dissolves Surface oxides (⬆️SE to give Clean Surface) -Prevents oxidation of solder Alloy in liquid state -⬆️Flow of molten Metal -⬇️Melting temp of solder Alloy -Makes area of soldering Physically w Chemically (n.1)Clean |
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Soldering Tech |
-Free hand soldering -Investment soldering |
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1)Free hand : -GR not acc -used in 2)MCQ Investment soldering : - Covering area not included in soldering by w As w thus -GR soldering Investment based on Quartz -What should be used for melting thr solder |
1) -bec of possibility of movement -Orthodontic 2) -antiflux.... Graphite w FeO or CaCO3... Preventing distortion of parent metals -as it has low Setting w thermal Expansion -reducing zone (Blue zone) of flame |
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GR : Soldering Failure |
-Melting of Alloy in oxi zone -Thick Solder (weak w porous) -insufficient or improper Flux -antiflux spreads to area of Flux -Porosity |
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GR porosity |
-Overheating (by vapor of base metals) -Improper Flux -Use of Oxi zone -Thick Solder |
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Eff of Overheating of Solder |
-Diffusion of Solder into Casting ➡️ dec strength w ductility -Porosity -Softening heat treatment as it causes Recrystallization w weld decay |
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Welding لحام من غير ما احط حاجة في النص(solder) -Def -includes |
-Joining of 2 metals or alloys without using 3 one (solder) -Pressure Welding -Laser Welding -Spot Welding |
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1)Pressure :causes 2)Laser : app of 3)Spot : -in case of -depends on -pieces of Metal are placed between -If parts to be joined are -Materials like cannot Spot welded |
1)their Adhesion 2)controlled laser beam 3) -St Steel w Co-Cr alloys -resistance of Alloy -2 electrodes -Poor Electric conductor -Gold (high Electric conductor) |
