24410
It is suggested that the extremely favorable friction properties are caused by a tribochemical reaction between the 1 , 3 - diketones and the steel surfaces , leading to formation of a chelated iron - diketo complex .
 1 , 3 - diketones, iron, diketo
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 1 , 3 - diketones, iron, diketo