Collection: Diamond Suspension

Beta Diamond Products supplies monocrystalline and polycrystalline diamond polishing suspensions for all stages of metallographic and petrographic specimen preparation. Available in water-based and oil-based carrier formulations with diamond particle sizes from 0.1 to 60 microns, our suspensions are engineered for consistent particle size distribution, stable suspension without settling, and repeatable polishing results across automated and manual preparation systems.

Monocrystalline vs. Polycrystalline Diamond Suspension: How to Select

Monocrystalline diamond suspension contains intact diamond crystals with defined crystal facets. These crystals maintain their geometry during polishing, producing a high, consistent material removal rate. Monocrystalline suspension is the correct choice for hard and brittle materials including cemented carbides (WC-Co), alumina ceramics (Al₂O₃), zirconia (ZrO₂), silicon carbide, hardened tool steels (HRC 60+), and chromium carbide thermal spray coatings.

Polycrystalline diamond suspension contains diamond particles with multiple crystallographic planes that fracture progressively during polishing, exposing fresh cutting edges — a self-sharpening mechanism that produces a finer scratch pattern at equivalent micron sizes compared to monocrystalline. Polycrystalline is preferred for all intermediate and final polishing of metals and alloys, and is the required choice for applications demanding a deformation-minimized surface finish, including electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) sample preparation, and orientation imaging microscopy (OIM).

Material-Specific Suspension Selection

Material	Approx. Hardness	Recommended Type	Final Step
Cemented carbide (WC-Co)	HRA 85–93	Monocrystalline	1μm mono diamond
Alumina ceramics (Al₂O₃)	HV 1500–2000	Monocrystalline	1μm mono, then colloidal silica
Hardened tool steel (HRC 60+)	HV 700–900	Monocrystalline	1μm mono or 0.25μm poly
IN718 / nickel superalloys	HV 350–450	Polycrystalline	0.25μm poly, then colloidal silica
Ti-6Al-4V (titanium alloy)	HV 320–360	Polycrystalline	0.25μm poly + OPS colloidal silica
316L stainless steel	HV 200–250	Polycrystalline	0.25μm poly, OPS if EBSD required
Aluminum alloys	HV 60–150	Polycrystalline	0.25μm poly + OPS colloidal silica
Rock / mineral specimens	Variable	Polycrystalline	1μm poly (polished sections)
Silicon / GaN / compound semiconductors	HV 1000+ (substrate)	Colloidal silica (final only)	0.06μm colloidal silica only

Carrier Selection: Water-Based vs. Oil-Based

Water-based carrier: Preferred for automated polishing systems with integral dispensers (Buehler Burst, Struers DiaDuo-2), for hydrophilic polishing cloths, and when rapid cleanup between steps is required. Not suitable for reactive metals (magnesium, uranium) that corrode in aqueous environments.

Oil-based carrier: Provides longer working time without evaporation — essential for manual polishing cycles. Preferred for reactive metals, applications requiring controlled lubrication, and when the preparation sequence involves extended polishing steps without periodic re-application.

System Compatibility

All Beta Diamond diamond suspensions are compatible with: Buehler AutoMet 250, Ecomet 30/60/300, Vector Power Head, Metaserv 250; Struers LaboPol-5/21, Tegrapol-21/31, Tegramin-20/25/30; LECO VP-160, VP-50; and all other automated and manual grinder-polisher systems. Contact us to confirm compatibility with any unlisted system or to obtain dispensing recommendations for automated systems.

Frequently Asked Questions

What micron size diamond suspension is used for final polishing in metallography?

The final diamond polishing step for most metallographic applications uses 1 micron (1μm) or 0.25 micron (0.25μm) polycrystalline diamond suspension, depending on the material and the required surface quality. For EBSD analysis and deformation-sensitive materials (titanium alloys, magnesium, aluminum alloys, austenitic stainless steels), the final diamond step is followed by a chemomechanical polishing step using 0.06 micron colloidal silica or 0.05 micron alumina on a chemomechanical polishing cloth. This removes the thin residual deformation layer introduced by mechanical polishing and is required to obtain clear Kikuchi patterns in the SEM.

What is the difference between diamond suspension and diamond compound?

Diamond suspension is a liquid (water- or oil-based) dispersion of diamond particles dispensed directly onto a rotating polishing cloth. Diamond compound (paste) is a viscous, oil-based medium applied manually. Suspension is preferred for automated polishing systems with dispensers; compound is preferred for manual polishing and lapping operations. Both achieve equivalent surface finish quality at equivalent micron sizes when used correctly with matched polishing cloths and lubricants.

Can I use Beta Diamond diamond suspension with my Buehler, Struers, or Allied High Tech polisher?

Yes. All Beta Diamond diamond suspensions are direct drop-in replacements for Buehler MetaDi Supreme and Struers DiaPro series suspensions, Allied High Tech suspensions, on any Buehler, Struers, Allied High Tech, or other manufactuerer polishers. Contact us with your specific model and dispensing system if you require a dispenser connector confirmation or need recommended cycle parameters for your preparation method.

How should diamond suspension be stored?

Store at room temperature (15–25°C), away from direct sunlight. Shelf life is 24 months from manufacture in sealed original containers.