The use of boron nitride ceramic and zirconia ceramic nozzles in different processes of powder metallurgy

 In powder metallurgy (PM) processes, boron nitride and zirconia ceramic nozzles are used depending on the type of metal materials.

 

 

Main Features of Ceramic Nozzles

 

High-temperature resistance: withstands temperatures above 1500 °C from molten metals or plasma flames.

 

Wear resistance: resists erosion from powder or gas flow for long-term operation.

 

Chemical inertness: does not react with active metals or gases.

 

 

Applications at Different Stages of Powder Metallurgy

Stage	Process	Functions of Nozzles	Ceramic Nozzles	Typical Metals
Powder Preparation	Gas Atomization	High-pressure inert gas (such as nitrogen or argon) impinges on the molten metal stream to form fine powder; ceramic nozzles control flow and particle size.	Boron Nitride and Zirconia	High-purity or reactive metals such as titanium and nickel-based alloys.
	Water Atomization	Ceramic nozzles provide corrosion resistance and precise flow control.	Zirconia	Used in high-pressure water atomization for preparing low-cost powders such as iron-based powders.
Powder Spraying or Deposition	Thermal Spraying	During coating or preform preparation (e.g., plasma spraying or HVOF), ceramic nozzles spray metal powders onto substrates to form dense coatings.	Boron Nitride and Zirconia	Applicable to all metal powders.
Powder Transportation and Treatment	Fluidized Bed or Pneumatic Transportation	Ceramic nozzles are used to control gas flow, evenly disperse or convey powders, and prevent agglomeration or clogging.	Boron Nitride and Zirconia	Tungsten, molybdenum, iron, cobalt, nickel, aluminum, titanium, tantalum, and other active metal powders.
Treatment After Sintering	Cooling or Atmosphere Control	Ceramic nozzles spray inert gases (e.g., hydrogen, nitrogen) or cooling media to control furnace atmospheres and accelerate part cooling to prevent oxidation.	Boron Nitride and Zirconia	High-performance metal powders such as high-speed steel, titanium alloys, and amorphous/metallic glass powders.
3D Printing (e.g., Binder Jetting)	–	Ceramic nozzles are used to accurately spray binders or metal slurries.	Boron Nitride and Zirconia	Powder metallurgy additive manufacturing applications.
Degreasing or Cleaning	–	Ceramic nozzles are used to remove temporary binders or residual powder from compacts.	Zirconia	Titanium and its alloys, nickel-based superalloys, aluminum alloys, cobalt-chromium alloys, refractory metals (tungsten, tantalum, molybdenum), precious metals (gold, silver, platinum), and high-entropy alloys.

 

Table 1: Boron Nitride Ceramic Nozzle Properties

Properties	Units	BMA	BSC	BMZ	BSN
Main Composition	–	BN + Zr + Al	BN + SiC	BN + ZrO₂	BN + Si₃N₄
Color	–	White Graphite	Greyish-Green	White Graphite	Dark Gray
Density	g/cm³	2.25–2.35	2.4–2.5	2.8–2.9	2.2–2.3
Three-Point Bending Strength	MPa	65	80	90	150
Compressive Strength	MPa	145	175	220	380
Thermal Conductivity	W/m·K	35	45	30	40
Thermal Expansion Coefficient (20–1000 °C)	10⁻⁶/K	2.0	2.8	3.5	2.8
Max Using Temperature (Atmosphere / Inactive Gas / High Vacuum)	°C	900 / 1750 / 1750	900 / 1800 / 1800	900 / 1800 / 1800	900 / 1800 / 1800
Room Temperature Electric Resistivity	Ω·cm	>10¹³	>10¹²	>10¹²	>10¹³
Typical Applications	–	Powder metallurgy, metal casting, high-temperature furnace components, crucibles, casting molds for precious and special alloys, high-temperature supports, and nozzles or transport tubes for molten metals.

 

Table 2: Zirconia Ceramic Nozzle Indicators

Indicators	Item	Units	MSZ-H	MSZ-L	Custom
Main Composition	ZrO₂	%	≥95	≥95	60–95
	Al₂O₃	%	≤0.2	≤0.2	0.2–20
	SiO₂	%	≤0.4	≤0.4	0.2–1
	MgO	%	≤2.9	≤2.9	MgO / Y₂O₃
	Fe₂O₃	%	≤0.1	≤0.1	0.1–0.3
	TiO₂	%	≤0.1	≤0.1	0.1–1.0
Physical Properties	Color	–	Yellow	Yellow	Yellow / White
	Density	g/cm³	≤5.2	5.4–5.6	4.6–5.6
	Porosity	%	≤18.5	≤8	1–18.5
The stabilizers, grain composition, and porosity can be customized according to specific operating environments.