213

8

Ashless Antiwear and

Extreme-Pressure Additives

Liehpao Oscar Farng

CONTENTS

8.1 Introduction ........................................................................................................................... 214
8.2 Chemistry, Properties, and Performance (Classifi ed by Elements) ...................................... 215
8.2.1 Sulfur Additives ........................................................................................................ 215
8.2.1.1 Sulfurized Olefi ns ....................................................................................... 216
8.2.1.2 Sulfurized Esters and Sulfurized Oils ........................................................ 219
8.2.1.3 Other Sulfur Additives ................................................................................ 220
8.2.2 Phosphorus Additives ................................................................................................ 220
8.2.2.1 Phosphate Esters ......................................................................................... 221
8.2.2.2 Phosphites ................................................................................................... 222
8.2.2.3 Dialkyl Alkyl Phosphonates ....................................................................... 224
8.2.2.4 Acid Phosphates ......................................................................................... 225
8.2.3 Sulfur–Phosphorus Additives ................................................................................... 225
8.2.3.1 Ashless Dithiophosphates ........................................................................... 225
8.2.3.2 Ashless Phosphorothioates and Thiophosphates ........................................ 226
8.2.4 Sulfur–Nitrogen Additives ........................................................................................ 228
8.2.4.1 Dithiocarbamates ........................................................................................ 228
8.2.4.2 Dimercaptothiadiazole and Mercaptobenzothiazole Additives.................. 229
8.2.4.3 Other Sulfur–Nitrogen Additives ............................................................... 230
8.2.5 Phosphorus–Nitrogen Additives ............................................................................... 231
8.2.5.1 Amine Phosphates ...................................................................................... 231
8.2.5.2 Amine Thiophosphates and Dithiophosphates ........................................... 232
8.2.5.3 Other Phosphorus–Nitrogen Additives ....................................................... 232
8.2.6 Nitrogen Additives .................................................................................................... 23 2
8.2.7 Additives with Multiple Elements ............................................................................. 234
8.2.8 Halogen Additives ..................................................................................................... 23 5
8.2.9 Nontraditional Antiwear/Extreme-Pressure Additives ............................................. 236
8.3 Manufacture, Marketing, and Economics............................................................................. 237
8.4 Evaluation Equipment/Specifi cation ..................................................................................... 238
8.4.1 Lubricant Specifi cations ............................................................................................ 238
8.4.2 Additive Specifi cations .............................................................................................. 239
8.4.3 Test Methods and Equipment .................................................................................... 239
8.5 Outlook ................................................................................................................................. 243
Acknowledgment ........................................................................................................................... 245
References ...................................................................................................................................... 246