Surface technology

PVD processes....................................................................................................... 7

Gas flow regimes................................................................................................... 7

Vacuum production................................................................................................ 8

Molecular flow..................................................................................................... 8

Evacuation time................................................................................................ 11

PUMPING SYSTEM............................................................................................. 12

ROTARY PUMPS.............................................................................................. 12

DIFFUSION PUMPS......................................................................................... 13

TURBOMOLECULAR PUMPS............................................................................14

CRYOPUMPS................................................................................................... 15

VACUUM GAUGES............................................................................................. 16

CAPACITANCE VACUUM GAUGE......................................................................16

PIRANI VACUUM GAUGE.................................................................................16

IONIZATION VACUUM GAUGES.......................................................................16

STRUCTURE OF COATINGS AND THIN FILMS........................................................18

EFFECT OF ENERGETIC PARTICLES.................................................................20

SINTERING........................................................................................................... 20

DRIVING ENERGY.............................................................................................. 21

TRANSPORT MECHANISMS................................................................................22

HOT PRESSING.................................................................................................. 25

PVD PROCESSES.................................................................................................. 27

VACUUM EVAPORATION.................................................................................. 27

DEPOSITION GEOMETRY............................................................................. 29

DEPOSITION RATE....................................................................................... 30

THICKNESS UNIFORMITY............................................................................. 30

CONFORMAL COVERAGE.............................................................................31

FILM PURITY................................................................................................ 31

EVAPORATION SOURCES............................................................................. 32

PROCESS CONTROL.................................................................................... 34

ADVANTAGES OF VACUUM EVAPORATION...................................................35

DISADVANTAGES OF VACUUM EVAPORATION..............................................35

APPLICATIONS OF VACUUM EVAPORATION..................................................36

PLASMA SPRAY............................................................................................... 38

SPUTTERING......................................................................................................... 39

PLASMA............................................................................................................. 39

SPUTTERING..................................................................................................... 42

Sputter deposition......................................................................................... 43

SPUTTERING OF ALLOYS............................................................................. 43

THERMAL HISTORY OF THE SUBSTRATE......................................................44

SPUTTERING PROCESSES...........................................................................44

Transport of sputtered species...................................................................48

Process controll.......................................................................................... 48

Contamination............................................................................................ 49

Advantages of sputter deposition...............................................................49

Disadvantages of sputter deposition..........................................................50

Applications of sputter deposition..............................................................50

ARC PLASMA DEPOSITION.................................................................................... 50

MACROS......................................................................................................... 52

“STIRRED ARC TECHNIQUE”..........................................................................52

Advantages of arc deposition.....................................................................53

ION BEAM ASSISTED DEPOSITION........................................................................54

HIGH POWER PULSED MAGNETRON SPUTTERING................................................55

PLASMA IMMERSION ION IMPLANTATION..............................................................56

COATINGS FOR TRIBOLOGICAL APPLICATIONS.....................................................57

COATING FAILURE.............................................................................................. 57

COATING COMPOSITION.................................................................................... 58

Required PROPERTIES for TRIBOLOGICAL COATINGS........................................58

SCRATCH TEST............................................................................................... 60

Parameters of the SCRATCH test................................................................61

CONTACT STRESSES ANALYSIS......................................................................61

Coating STRUCTURES....................................................................................... 63

RESIDUAL STRESSES............................................................................................ 66

MEASUREMENT of residual stresses...............................................................66

Stresses in PVD.............................................................................................. 68

Stresses in CVD............................................................................................. 68

FATIGUE RESISTANCE OF COATED COMPONENTS.................................................68

NiP coating - fatigue resistance.....................................................................68

Cr coating - fatigue resistance.......................................................................69

Zn coating - fatigue resistance......................................................................69

ATMOSPHERIC PLASMA PROCESSES....................................................................70

Atmospheric plasma vs low pressure plasma................................................70

How is it possible to obtain cold plasma at atmospheric pressure?..................70

Corona discharge........................................................................................... 71

Atmospheric pressure plasma jets.................................................................71

Applications of cold plasma..............................................................................72

Surface activation of polymers......................................................................72

Deposition of coatings...................................................................................72

Structure of coatings deposited by atmospheric plasma............................73

Deposition rate........................................................................................... 73

Future applications of atmospheric plasma jets................................................73

Conclusions....................................................................................................... 73

CVD processes for SURFACE TREATMENT.............................................................74

Thermochemical treatments............................................................................. 74

MAIN STEPS OF THERMOCHEMICAL PROCESSES...........................................75

CARBURIZING................................................................................................ 75

GAS CARBURIZING..................................................................................... 76

PLASMA CARBURIZING............................................................................... 80

NITRIDING...................................................................................................... 80

Comparison NITRIDING vs CARBURIZING...................................................80

COMPOSITION of the final component AFTER NITRIDING............................81

KINETICS..................................................................................................... 81

SUBSTRATE TREATMENT............................................................................. 82

Nitriding of STAINLESS STEELS...................................................................82

GAS NITRIDING process..............................................................................82

PLASMA NITRIDING..................................................................................... 84

OXIDIZING TREATMENT...............................................................................86

NITRIDING OF ALUMINUM ALLOYS...............................................................86

PROPERTIES of NITRIDED or CARBURISED components.................................87

THEORY FROM EXERCISES................................................................................... 89

RECAP on ELASTIC BEHAVIOUR.....................................................................89

VACUUM PUMPS................................................................................................... 97

ROTARY PUMPS – medium vacuum................................................................97

DIFFUSION PUMPS – high vacuum.................................................................97

TURBOMOLECULAR PUMPS – high or ultra-high vacuum...............................98

CRYOPUMPS – high or ultra-high vacuum......................................................98

VACUUM GAUGES................................................................................................. 99

–8

CAPACITANCE VACUUM GAUGE – from 1 to 10 bar, but 4 orders of

magnitude max with single instrument.........................................................99

—7

PIRANI VACUUM GAUGE – 1 to 10 bar.........................................................99

—5 —13

IONIZATION VACUUM GAUGES – 10 to 10 bar.........................................99

STRUCTURE OF COATINGS AND THIN FILMS........................................................99

SZM – effect of IMPURITIES..........................................................................101

SZM – effect of ENERGETIC PARTICLES........................................................101

SINTERING......................................................................................................... 102

TRANSPORT MECHANISMS..............................................................................102

HOT PRESSING................................................................................................ 104

PVD PROCESSES................................................................................................ 105

VACUUM EVAPORATION................................................................................ 105

Deposition GEOMETRY..............................................................................107

Deposition RATE....................................................................................... 107

Thickness UNIFORMITY............................................................................. 107

CONFORMAL coverage (substrate at every inclination coated with the same

thickness)................................................................................................. 107

Film PURITY.............................................................................................. 108

EVAPORATION SOURCES...........................................................................108

Process CONTROL & EQUIPMENT..............................................................109

ADVANTAGES OF VACUUM EVAPORATION.................................................110

DISADVANTAGES OF VACUUM EVAPORATION............................................110

APPLICATIONS OF VACUUM EVAPORATION................................................111

PLASMA SPRAY............................................................................................. 112

WEB COATING.............................................................................................. 113

PLASMA.............................................................................................................. 113

SPUTTERING................................................................................................... 116

Sputter deposition....................................................................................... 116

SPUTTERING OF ALLOYS...........................................................................116

THERMAL HISTORY OF THE SUBSTRATE....................................................117

SPUTTERING PROCESSES.........................................................................117

Sputtering deposition process CONTROL PARAMETERS............................120

CONTAMINATION SOURCES in sputtering deposition................................120

Advantages of sputter deposition.............................................................121

Disadvantages of sputter deposition........................................................121

Applications of sputter deposition............................................................121

ARC PLASMA DEPOSITION.................................................................................. 121

Stirred arc.................................................................................................... 122

Macros......................................................................................................... 122

REACTIVE arc deposition.............................................................................122

ADVANTAGES of arc deposition....................................................................123

APPLICATIONS of arc deposition..................................................................123

ION BEAM ASSISTED vacuum evaporation deposition.......................................123

HIGH POWER PULSED MAGNETRON SPUTTERING..............................................124

PLASMA IMMERSION ION IMPLANTATION............................................................124

COATINGS FOR TRIBOLOGICAL APPLICATIONS...................................................125

Coating COMPOSITION.................................................................................... 125

Required PROPERTIES for TRIBOLOGICAL COATINGS......................................126

SCRATCH TEST............................................................................................. 127

Parameters of the SCRATCH test..............................................................127

CONTACT STRESSES ANALYSIS........................................................................128

Coating STRUCTURES..................................................................................... 129

RESIDUAL STRESSES.......................................................................................... 132

MEASUREMENT of residual stresses.............................................................132

Stresses in PVD............................................................................................ 133

Stresses in CVD........................................................................................... 134

FATIGUE RESISTANCE OF COATED COMPONENTS...............................................135

NiP coating - fatigue resistance...................................................................135

Cr coating - fatigue resistance.....................................................................135

Zn coating - fatigue resistance....................................................................135

ATMOSPHERIC PLASMA PROCESSES..................................................................136

Atmospheric plasma vs low pressure plasma..............................................136

How is it possible to obtain cold plasma at atmospheric pressure?................136

Corona discharge......................................................................................... 137

Atmospheric pressure plasma jets...............................................................137

APPLICATIONS of cold plasma.........................................................................138

Surface activation of polymers....................................................................138

Deposition of coatings.................................................................................138

Structure of coatings deposited by atmospheric plasma..........................138

Deposition rate in atmospheric plasma....................................................139

Future applications of atmospheric plasma jets..............................................139

Conclusions..................................................................................................... 139

CVD processes for SURFACE TREATMENT...........................................................141

Thermochemical treatments...........................................................................141

MAIN STEPS of THERMOCHEMICAL PROCESSES...........................................141

CARBURIZING.............................................................................................. 142

CARBURIZING PROCESS........................................................................... 142

GAS CARBURIZING................................................................................... 143

PLASMA CARBURIZING............................................