A water-based metalworking fluid is comprised of a polymeric boron species which includes at least B, N and H, together with a surfactant operable to provide an emulsion of the boron species with water. The polymeric boron species may be a polyborane or a borazine polymer and may be configured as a polyborane or borazine polymer backbone having side chains pendent thereupon. The side chains may include silicon and/or phosphorous. The silicon may be in the form of a silane or a siloxane species, including polymeric species. Disclosed are specific compositions as well as methods for using the compositions and methods for making the compositions.