Diamond Polycrystals Nozzles
Development of Method of Manufacturing Stream-Forming Nozzles and Mouth-Pieces from Diamond Polycrystals for Plants of Gas- and Fluid-Abrasive Treatment
Tech Area / Field
8 Project completed
Senior Project Manager
Latynin K V
MISIS (Steel and Alloys), Russia, Moscow
- NIKIMT (Institute of Assembly Technology), Russia, Moscow
- Sigma Pumpy Hranice, s.r.o, Czechia, Hranice\nPROCER Water Jet - Technology Components and Nozzles, France, Saint Louis
Project summaryProject Urgency. Stream forming nozzles and mouth-pieces are used for gas-abrasive treatment and wet blasting processing of various materials (metals, ceramics, various rock kinds etc.). Treatment of products is performed by impact of abrasive particles (high-silica sand as a rule); these particles are forced through the nozzle in gas or liquid stream with large speed. By means of such unit the following kinds of treatment are possible: blank cutting of various materials, especially in case when flame cutting is absolutely impossible (for example, for cutting of composite materials with organic ingredients, for disposal of obsolete worn equipment etc.), or if heating of the material to be cut is undesirable taking into account possible structure destruction or changes in strength characteristics (deposit removal from internal pipe surface in various heat exchanging systems, because it is possible to apply flexible small-diameter long supply hoses (catheters) etc.).
Application of such units at nuclear power stations for repair and dismantling works, as well as at disposal of obsolete surface and submarine ships is extremely promising. The method is fire and explosion safe (hydrogen emission at nuclear object is not observed); when applying this method no environment harmful dust is generated (cutting waste is captured by water which can be purified effectively); the units are compact; robotic equipment to be used in hazardous zones can be developed on their basis.
Until recent time mineral ceramics, corundum, sapphire or hard metal alloys have been used as materials for nozzles and mouth-pieces. Working effectiveness of units with such accessories is not very high because working life time of nozzles and mouth-pieces made of those materials is low. For example, durability of corundum nozzle at hydro stream pressure of 25 atm. and at abrasive (high-silica sand) consumption of 10 g/ min. is less than 4 minutes. Therefore, application field for such units has been quite restricted until recent time.
In MISiS new approaches have been developed for design of diamond polycrystal highly resistant against abrasive wearing as well as against its treatment process, which gives the opportunity to obtain products with desired shape, and diamond solidity parameters are not decreased at the same time. Quality of diamond polycrystals and their operation characteristics shall be defined mostly by the following parameters: abrasive properties, polycrystal dimensions and grain size in polycrystal structure. In MISiS realization means for special methods are developed; they help to perform total checking of diamond polycrystals’ quality; these special methods allow to control the grade of graphite-diamond transfer in polycrystals as well as existence of pores, cracks and large metallic inclusions. Along with high quality of initial raw material, this method allows obtaining products with guaranteed operational parameters.
The Project Goals are: scientific, technological and hardware support of applied in gas-abrasive treatment and wet blasting processing of various materials diamond polycrystal stream forming nozzles and mouth-pieces manufacture.
Tasks solved by the Project:
- Development of diamond polycrystals highly resistant against abrasive wearing;
- Development of diamond polycrystal quality nondestructive check;
- Development of diamond polycrystal stream forming nozzles and mouth-pieces making methods.
Main expected scientific and technical results (products) to be obtained upon the Project completion:
- Diamond polycrystals with high solidity and wear resisting property;
- Improved stream forming nozzles and mouth-pieces manufacturing technique;
- Diamond polycrystal nondestructive checking method;
- Extension of nozzles and mouth-pieces application fields.
It is expected to perform development patenting, legalization of know-how for certain operations, writing articles for scientific and technical periodicals.
The following achievements shall be possible upon the Project accomplishment:
- Development of diamond nozzles with stable wear resistant characteristics and quality properties, which shall overcome sapphire ones in wear resistance.
- Development of diamond mouth-pieces with stable wear resistant characteristics and quality properties, which shall overcome hardmetal ones in wear resistance.
Subject of Investigation and Development.
- Laser stream forming nozzle and mouth-piece manufacturing technique;
- Diamond polycrystal quality nondestructive checking methods;
- Experimental manufacture of stream forming nozzles and mouth-pieces;
- Expansion of nozzles and mouth-pieces application fields.
Description of technical solution methods and ways applied.
Polycrystal diamonds obtained from carbon-bearing materials are composite materials consisting of diamond phase grains and metal-ceramic bonding agent.
Strength properties of diamond polycrystals depend on the following factors:
- grain size depends on the speed of phase graphite-diamond change and on the speed of metal-ceramic bonding agent penetration into graphite structure, or on castability and adhesion of the bonding agent as regards graphite;
- strength properties of the bonding agent depend directly on its composition;
- microstress level depends on ratio of metal and diamond components’ lattices parameters of diamond polycrystals at different pressure and temperature values;
- contents of non-diamond carbon in diamond polycrystal structure depends, first of all, on graphitization degree of initial graphite and on graphitization speed in contact with the metal-ceramic bonding agent.
Therefore, alloyage performed by various metal components (Ni or Ni-Cr alloy) provides the opportunity to influence diamond polycrystal properties positively and within the wide bounds, including their thermal resistance.
New features in laser technique applied in making nozzle and mouth-piece channel are: computer programmable control of the beam parameters and of billet holding three-axis table traveling. This technique allows reducing machine time for the channel processing; it gives the opportunity to obtain nozzles with irregular opening shape, to improve parameters of internal channel surface roughness upon laser treatment down to
Rz = 2.5 – 0.63 and to reduce cut width down to 0.1 mm at the depth of 3 mm.
Developed objects specific parameter values and properties description.
а. properties of diamond polycrystals upon sorting by means of non-destructive checking method.
- abrasive ability up to 30 cm3 mg;
- dimensions Ø up to 8 mm;
b. parameters of nozzle laser treatment:
- time for nozzle channel manufacture not more than 7 min.;
- roughness of the channel surface Rz = 2.5 – 0.63
c. operation characteristics of nozzles:
- wear resistance at least 4 hours at hydrostream pressure of 25 atm., abrasive agent consumption 10 g/ min.