Yes there are several ways to do that... one is you can change permissions for user groups to 0 (can't post new topics) and (can't respond to topics). The other is to lock the posts in that forum (takes a bit of doing) there is another way but I can't think of it off the top of my head at the moment. I am sure the others here will have a better/faster way to do it though.
Dunny
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Dunny
Removed link due to bleedover spammers
Dawn of Iskirra