scholarly journals The relationship between the laser damaged threshold and step velocity in different supersaturation regions

RSC Advances ◽  
2018 ◽  
Vol 8 (64) ◽  
pp. 36453-36458
Author(s):  
Weidong Li ◽  
Yu Li ◽  
Shenglai Wang ◽  
Wenyong Cheng
Keyword(s):  
Potassium Dihydrogen Phosphate ◽  
Nanosecond Laser ◽  
Dihydrogen Phosphate ◽  
Potassium Dihydrogen ◽  
Step Velocity ◽  
The Relationship ◽  
Kdp Crystals

The laser damaged threshold (LDT) of potassium dihydrogen phosphate (KDP) crystals grown at different supersaturation points were investigated using a Nd:YAG nanosecond laser.

scholarly journals The Strain Rate Sensitivity and Creep Behavior for the Tripler Plane of Potassium Dihydrogen Phosphate Crystal by Nanoindentation

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 369
Author(s):  
Jianhui Mao ◽  
Wenjun Liu ◽  
Dongfang Li ◽  
Chenkai Zhang ◽  
Yi Ma
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Creep Deformation ◽  
Potassium Dihydrogen Phosphate ◽  
Rate Sensitivity ◽  
Dislocation Nucleation ◽  
Machining Process ◽  
Dihydrogen Phosphate ◽  
Potassium Dihydrogen ◽  
Kdp Crystals

As an excellent multifunctional single crystal, potassium dihydrogen phosphate (KDP) is a well-known, difficult-to-process material for its soft-brittle and deliquescent nature. The surface mechanical properties are critical to the machining process; however, the characteristics of deformation behavior for KDP crystals have not been well studied. In this work, the strain rate effect on hardness was investigated on the mechanically polished tripler plane of a KDP crystal relying on nanoindentation technology. By increasing the strain rate from 0.001 to 0.1 s−1, hardness increased from 1.67 to 2.07 GPa. Hence, the strain rate sensitivity was determined as 0.053, and the activation volume of dislocation nucleation was 169 Å3. Based on the constant load-holding method, creep deformation was studied at various holding depths at room temperature. Under the spherical tip, creep deformation could be greatly enhanced with increasing holding depth, which was mainly due to the enlarged holding strain. Under the self-similar Berkovich indenter, creep strain could be reduced at a deeper location. Such an indentation size effect on creep deformation was firstly reported for KDP crystals. The strain rate sensitivity of the steady-state creep flow was estimated, and the creep mechanism was qualitatively discussed.

scholarly journals Elastic-plastic-brittle transitions of potassium dihydrogen phosphate crystals: characterization by nanoindentation

2020 ◽  
Vol 8 (4) ◽  
pp. 447-456
Author(s):  
Yong Zhang ◽  
Ning Hou ◽  
Liang-Chi Zhang ◽  
Qi Wang
Keyword(s):  
Plastic Deformation ◽  
Brittle Fracture ◽  
Optical Switching ◽  
Potassium Dihydrogen Phosphate ◽  
Machining Process ◽  
Fracture Mechanisms ◽  
Dihydrogen Phosphate ◽  
Kdp Crystal ◽  
Potassium Dihydrogen ◽  
Kdp Crystals

AbstractPotassium dihydrogen phosphate (KDP) crystals are widely used in laser ignition facilities as optical switching and frequency conversion components. These crystals are soft, brittle, and sensitive to external conditions (e.g., humidity, temperature, and applied stress). Hence, conventional characterization methods, such as transmission electron microscopy, cannot be used to study the mechanisms of material deformation. Nevertheless, understanding the mechanism of plastic-brittle transition in KDP crystals is important to prevent the fracture damage during the machining process. This study explores the plastic deformation and brittle fracture mechanisms of KDP crystals through nanoindentation experiments and theoretical calculations. The results show that dislocation nucleation and propagation are the main mechanisms of plastic deformation in KDP crystals, and dislocation pileup leads to brittle fracture during nanoindentation. Nanoindentation experiments using various indenters indicate that the external stress fields influence the plastic deformation of KDP crystals, and plastic deformation and brittle fracture are related to the material’s anisotropy. However, the effect of loading rate on the KDP crystal deformation is practically negligible. The results of this research provide important information on reducing machining-induced damage and further improving the optical performance of KDP crystal components.

Kinetics of Potassium Dihydrogen Phosphate Single-Crystal Growth Mapped by the Chemical Bond Simulation

2012 ◽  
Vol 554-556 ◽  
pp. 31-34 ◽  
Author(s):  
Xu Zhang ◽  
De Xiang Jia
Keyword(s):  
Chemical Bond ◽  
Crystal Morphology ◽  
Potassium Dihydrogen Phosphate ◽  
Dihydrogen Phosphate ◽  
Chemical Bonds ◽  
Potassium Dihydrogen ◽  
Solution Interface ◽  
Shape Controlled ◽  
Kinetics Of ◽  
Kdp Crystals

A chemical bond simulation was proposed to quantitatively calculate the growth rate from the kinetic model of the crystal-solution interface. When this approach was applied to the cases of potassium dihydrogen phosphate (KDP) crystals grown from the solution with different surpersaturation, the growth behaviors of KDP crystals were predicted and the calculated results were consistent with the experimental data. These results demonstrate that regulating the distribution of the chemical bonds between the crystal and solution interfaces can effectively control the crystal morphology. Seeding experiments with the chemical bond simulation may have significant potential towards the development of shape-controlled growth with defined conditions.

Studies of Potassium Dihydrogen Phosphate (KDP) Crystals Doped with Potassium Dichromate (PD) using ICP and UV Spectrophotometer

2007 ◽  
Vol 1015 ◽  
Author(s):  
Selemani Seif ◽  
Ravindra Behari Lal
Keyword(s):  
Potassium Dichromate ◽  
Potassium Dihydrogen Phosphate ◽  
Dihydrogen Phosphate ◽  
High Concentration ◽  
Potassium Dihydrogen ◽  
Evaporation Technique ◽  
Uv Transmittance ◽  
Kdp Crystals ◽  
Specific Amount

AbstractThis paper reports on preparation and characterization of Potassium Dihydrogen Phosphate (KDP) crystals doped with Potassium Dichromate (PD). The crystals were grown at room temperature by solution evaporation technique. The grown crystals were polished, sliced, and analyzed using UV-Spectrophotometer, which showed high concentration of PD impurities in KDP crystals at 200-280 nanometer. These concentrations were then verified using ICP measurements to determine specific amount in ppm of chromium ions in KDP crystals. In additional to that, the UV-transmittance data of these crystals were then converted to absorbance per thickness, and used to calculate absorption coefficients, extinction coefficients, and refractive index as a function of wavelength. The results showed that the presence of PD impurities in the crystal matrix of KDP has played a key reformative role in the UV sensing of Potassium Diphosphate crystals.

Research on Deliquescent Polishing Fluid for KDP Crystals

2009 ◽  
Vol 626-627 ◽  
pp. 53-58 ◽  
Author(s):  
Shao Long Guo ◽  
Fei Hu Zhang ◽  
Yong Zhang ◽  
Dian Rong Luan
Keyword(s):  
Removal Rate ◽  
Potassium Dihydrogen Phosphate ◽  
Dihydrogen Phosphate ◽  
Kdp Crystal ◽  
Potassium Dihydrogen ◽  
Performance Requirements ◽  
Stability Experiment ◽  
Main Components ◽  
Polishing Fluid ◽  
Kdp Crystals

The characteristics and principle of deliquescent polishing technology for potassium dihydrogen phosphate (KDP) crystals are introduced, and the performance requirements of deliquescent polishing fluid for KDP crystals are proposed. The main components of the deliquescent polishing fluid for KDP crystals were selected according to these performance requirements. Through uniformity experiment, stability experiment and fluidity experiment, uniformity, stability and fluidity of deliquescent polishing fluid for KDP crystals prepared using the selected components were tested. Through deliquescent polishing experiment of KDP crystal, polishing performance of deliquescent polishing fluid compounded using the selected components was tested. The material removal rate of the KDP crystal in the deliquescent polishing experiment was 6.03μm/min, and the surface roughness of the KDP crystal after deliquescent polishing was 4.857nm. The experimental results show that the compounded deliquescent polishing fluid for KDP crystals has good polishing performance and can reach the requirements.

Elastic-Plastic Deformation of KDP Crystals under Nanoindentation

2013 ◽  
Vol 773-774 ◽  
pp. 705-711 ◽  
Author(s):  
Jing Peng ◽  
Liang Chi Zhang ◽  
Xin Chun Lu
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Potassium Dihydrogen Phosphate ◽  
Dislocation Nucleation ◽  
Dihydrogen Phosphate ◽  
Potassium Dihydrogen ◽  
Diamond Indenter ◽  
The Common ◽  
Kdp Crystals ◽  
Yielding Point

This paper investigates the mechanical properties of potassium dihydrogen phosphate (KDP) crystals with the aid of nanoindentation using a conical diamond indenter. It was found that when unloading is after the first pop-in, the common method of obtaining elastic modulus from the unloading curve of nanoindentation is no longer applicable, because the unloading is inelastic. The study revealed that the pop-in could be due to dislocation nucleation and propagation, and that the first pop-in occurs under a stress below that of the major dislocation burst. Hence, the macroscopic yielding point, which is usually regarded as the onset of plasticity of a material, is nanoscopically not a critical point of the first dislocation in KDP. The study found that the elastic modulus of KDP indenting on its (001) plane is 52.8±3.8GPa. The hardness of the material is 1.89±0.05GPa.

Investigation on the influence of aerostatic pressure upon surface generation in flycutting

2018 ◽  
Vol 233 (4) ◽  
pp. 1136-1143 ◽  
Author(s):  
Congying Deng ◽  
Chenhui An ◽  
Bo Wei ◽  
Jianguo Miao
Keyword(s):  
Single Point ◽  
Complex Structure ◽  
Pressure Fluctuations ◽  
Potassium Dihydrogen Phosphate ◽  
Axial Direction ◽  
Surface Generation ◽  
Dihydrogen Phosphate ◽  
Machined Surface ◽  
Potassium Dihydrogen ◽  
The Relationship

Single-point diamond flycutting is an important technology for cutting flat KH2PO4 (potassium dihydrogen phosphate) crystals of large size. However, there always exist some undesirable waviness errors on the machined surface, which can directly reduce the optical performance of the potassium dihydrogen phosphate crystals. This article presents a kind of low-frequency waviness errors with wavelength about 26 mm along the feeding direction in single-point diamond flycutting, which has not been described yet. In order to find the main source of the mentioned waviness errors, the relationship between the displacement of the cutting tool and the aerostatic pressure was quantitatively studied for the first time. And then, surface simulation considering the aerostatic pressure fluctuations was carried out based on the relationship. Besides, a novel method that can achieve online submicron feeding along axial direction in single-point diamond flycutting without complex structure was proposed considering the spindle motion errors, the spindle dynamic characteristics and the aerostatic pressure. The experimental results validate that the mentioned waviness errors are mainly generated by the bolt stretched phenomenon and deformation of the big disk flycutting head due to the aerostatic pressure fluctuations. And the proposed method can achieve a cutting depth of about 120 nm when the aerostatic pressure increases from 0.52 to 0.56 MPa, which can reduce the cutting force and is beneficial for the performance of single-point diamond flycutting.

scholarly journals Modeling the mass transfer processes in the growth of KDP crystals from solution

2019 ◽  
Vol 21 (1) ◽  
pp. 26-34
Author(s):  
N. A. Verezub ◽  
V. L. Manomenova ◽  
A. I. Prostomolotov
Keyword(s):  
Mathematical Model ◽  
Aqueous Solution ◽  
Mass Transfer ◽  
Crystal Growth ◽  
Potassium Dihydrogen Phosphate ◽  
Dihydrogen Phosphate ◽  
Potassium Dihydrogen ◽  
Transfer Processes ◽  
Mass Transfer Processes ◽  
Kdp Crystals

Finding the conditions of high-speed single crystal growth with an appropriate quality is a priority for the industrial production of crystalline materials. Crystals of potassium dihydrogen phosphate (KDP) are important optical materials, they are grown from an aqueous solution and an increase in the rate of growth and quality of a single crystal is of great practical importance.In this paper, mathematical simulation of hydrodynamic and mass transfer processes in growing KDP crystals is performed. The flow and mass transfer are modeled within the framework of continuous medium, which is considered as an aqueous solution of a special salt — potassium dihydrogen phosphate. This salt dissolves in water to a saturation level at a high temperature. Then, such supersaturated solution is used to grow crystals at lower temperatures in non-flowing and flowing crystallizers. The mathematical model is considered in a conjugate formulation with allowance for mass transfer in the«solution—crystal» system. Local features of hydrodynamics and mass transfer in a solution near the surface of a growing crystal are determined, which can affect on the local (for a particular place and direction) crystal growth rate and the formation of defects. The requirements to the crystallizers that provide the «necessary» hydrodynamics in the solution are discussed. Its validation is shown for the flow around a long horizontal plate simulating the growing facet of the crystal. The rate of precipitation of salt was evaluated by the proposed mathematical model, which matches the calculation of solution flow according to the Navier-Stokes equations for an incompressible fluid with a thermodynamic condition for the normal growth of a face under conditions of two-dimensional nucleation. The action of the flowing crystallizers was analyzed for various solution inflows (axial and ring) and its outflow through the axial bottom hole.

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