You can make friends at work but to keep them make sure you interact with them outside of a work context. If they are just someone you talk to at your desk or

You can make friends at work but to keep them make sure you interact with them outside of a work context. If they are just someone you talk to at your desk or even go to lunch or drinks after work then if either of you changes job that context is removed. Meet up with them on weekends or evenings if you want to keep them.